JEE Main 11 April 2023 Shift 2 question paper with solutions
JEE Main 11 April 2023 Shift 2: all 90 questions in paper order (Maths, Physics, Chemistry) with the answer key and worked solutions. Free to read; attempt it as a timed 3-hour mock test.
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Maths
Question 1
Maths · Determinants · Single correct
If $$\left| \begin{array}{ccc} x+1 & x & x \\ x & x+\lambda & x \\ x & x & x+\lambda^2 \end{array} \right| = \frac{9}{8}(103x+81)$$, then $\lambda$, $\frac{\lambda}{3}$ are the roots of the equation
$4x^2 + 24x - 27 = 0$
$4x^2 - 24x - 27 = 0$
$4x^2 + 24x + 27 = 0$
$4x^2 - 24x + 27 = 0$
Answer: (d)
Solution
Given that, $$\begin{vmatrix} x+1 & x & x \\ x & x+\lambda & x \\ x & x & x+\lambda^2 \end{vmatrix} = \frac{9}{8}(103x + 81)$$ Put $x = 0$ as $x \in \mathbb{R}$ $$\begin{vmatrix} 1 & 0 & 0 \\ 0 & \lambda & 0 \\ 0 & 0 & \lambda^2 \end{vmatrix} = \frac{9}{8}(103(0) + 81)$$ On expanding the determinant we get, $$\Rightarrow \lambda^3 = \frac{9}{8} \times 81$$ $$\Rightarrow \lambda^3 = \frac{9^3}{2^3}$$ $$\Rightarrow \lambda = \frac{9}{2} and \frac{\lambda}{3} = \frac{9}{6}$$ Now the required quadratic equation is $$x^2 - \left(\frac{9}{2}\right)x + \frac{9}{2} \times \frac{9}{6} = 0$$ $$\Rightarrow x^2 - (6)x + \frac{27}{4} = 0$$ $$\Rightarrow 4x^2 - 24x + 27 = 0$$ Hence, the required quadratic equation is $4x^2 - 24x + 27 = 0$
Question 2
Maths · Three Dimensional Geometry · Single correct
Let the line passing through the points $P(2, -1, 2)$ and $Q(5, 3, 4)$ meet the plane $x - y + z = 4$ at the point $R$. Then the distance of the point $R$ from the plane $x + 2y + 3z + 2 = 0$ measured parallel to the line $\frac{x-7}{2} = \frac{y+3}{2} = \frac{z-2}{1}$ is
$\sqrt{61}$
$\sqrt{189}$
$\sqrt{31}$
3
Answer: (d)
Solution
Given, the line passing through the points $P(2, -1, 2)$ and $Q(5, 3, 4)$. So, the equation of line $PQ$ will be, $$\frac{x-2}{3} = \frac{y+1}{4} = \frac{z-2}{2} = \lambda$$ Now let point $R$ be $(3\lambda + 2, 4\lambda - 1, 2\lambda + 2)$. Given, $R$ lies on plane $x - y + z = 4$. Therefore, $$3\lambda + 2 - 4\lambda + 1 + 2\lambda + 2 = 4$$ $$\Rightarrow \lambda = -1$$ Therefore, $R(-1, -5, 0)$. Now let line $SR$ be: $$\frac{x+1}{2} = \frac{y+5}{2} = \frac{z}{1} = k$$ as it is parallel to $$\frac{x-7}{2} = \frac{y+3}{2} = \frac{z-2}{1}$$ and passing through $(-1, -5, 0)$. So, the point $S: (2k - 1, 2k - 5, k)$. Now $S$ lies on plane: $x + 2y + 3z + 2 = 0$. $$\Rightarrow (2k - 1) + (4k - 10) + 3k + 2 = 0$$ $$\Rightarrow 9k - 9 = 0 \Rightarrow k = 1$$ Hence, $S(1, -3, 1)$. So, distance $SR = \sqrt{4 + 4 + 1} = 3$.
Question 3
Maths · Binomial Theorem · Single correct
If the $1011^{\text{th}}$ term from the end in the binomial expansion of \[ \left(\frac{4x}{5}-\frac{5}{2x}\right)^{2022} \] is $1024$ times the $1011^{\text{th}}$ term from the beginning, then $32|x|$ is equal to
15
10
12
8
Answer: (b)
Solution
Given, the 1011th term from the end in the binomial expansion of $\left( \frac{4x}{5} - \frac{5}{2x} \right)^{2022}$ is 1024 times the 1011th term from the beginning. So, according to the question we have, $$\frac{T_{1013}}{T_{1011}} = 1024$$ $$\Rightarrow \frac{{^{2022}C_{1012} \left( \frac{4x}{5} \right)^{1010} \cdot \left( -\frac{5}{2x} \right)^{1012}}}{{^{2022}C_{1010} \left( \frac{4x}{5} \right)^{1012} \cdot \left( -\frac{5}{2x} \right)^{1010}}} = 1024$$ $$\Rightarrow \left( -\frac{5}{2x} \right)^2 = 1024 \left( \frac{4x}{5} \right)^2$$ $$\Rightarrow \frac{5^4}{2^6 x^4} = 2^{10}$$ $$\Rightarrow \left( \frac{5}{x} \right)^4 = 2^{16}$$ $$\Rightarrow |x| = \frac{5}{16}$$ $$\Rightarrow 32|x| = 10$$ Note this question was bonus in Jee Main 2023 April session as answer key was not matching, so we have modified the question.
Question 4
Maths · Integrals · Single correct
Let the function $f : [0, 2] \to \mathbb{R}$ be defined as $f(x) = \begin{cases} e^{\min \{ x^2, x - [x] \}}, & x \in [0, 1) \\ e^{[x - \log_e x]}, & x \in [1, 2] \end{cases}$, where $[t]$ denotes the greatest integer less than or equal to $t$. Then the value of the integral $\int_{0}^{2} x f(x) \, dx$ is
$1 + \frac{3e}{2}$
$(e - 1) \left(e^2 + \frac{1}{2}\right)$
$2e - 1$
$2e - \frac{1}{2}$
Answer: (d)
Solution
Given, $$f(x) = \begin{cases} \min \{ x^2, x - \lfloor x \rfloor \}, & x \in [0, 1) \\ e^{x - \log_e x}, & x \in [1, 2] \end{cases}$$ $$\Rightarrow f(x) = \begin{cases} e^{x^2} & x \in [0, 1) \\ e, & x \in [1, 2] \end{cases}$$ As $x - \ln x \in [1, 2)$ for $x \in [1, 2]$, so $[x - \ln x] = \{x\}$, so $x \in (0, 1)$, $x^2 < \{x\}$. Now solving the integral we get, $$\int_0^2 x f(x) = \int_0^1 x \cdot e^{x^2} \, dx + \int_1^2 x \cdot e \, dx$$ Now in first integral, let $x^2 = t \Rightarrow 2x \, dx = dt$ we get, $$\Rightarrow \int_0^2 x f(x) = \left[ \frac{1}{2} \int_0^1 e^t \, dt \right] + \left[ e \cdot \frac{x^2}{2} \right]_1^2$$ $$\Rightarrow \int_0^2 x f(x) = \left( e - \frac{1}{2} \right) + \frac{3e}{2}$$ $$\Rightarrow \int_0^2 x f(x) = 2e - \frac{1}{2}$$
Question 5
Maths · Differential Equations · Single correct
Let $y = y(x)$ be the solution of the differential equation $\frac{dy}{dx} + \frac{5}{x \left(x^5 + 1\right)} y = \frac{\left(x^5 + 1\right)^2}{x^7}$, $x > 0$. If $y(1) = 2$, then $y(2)$ is equal to
637
679
693
697
Answer: (c)
Solution
Given: $$ \frac{dy}{dx} + \frac{5}{x(1+x^5)}y = \frac{(1+x^5)^2}{x^7} $$ This is a linear differential equation. I.F. = $$ e^{\int \frac{5}{1+x^5} dx} $$ $\($ $\Rightarrow$ $\)$ I.F. = $$ e^{\int \frac{5x^5}{x(1+x^5)} dx} $$ $\($ $\Rightarrow$ $\)$ I.F. = $$ e^{\int \frac{5}{x(1+x^5)} dx} $$ $\($ $\Rightarrow$ $\)$ I.F. = $$ e^{-\int \frac{-5}{x^5+1} dx} $$ $\($ $\Rightarrow$ $\)$ I.F. = $$ e^{-\int \frac{d(x^{-5}+1)}{x^{-5}+1}} $$ $\($ $\Rightarrow$ $\)$ I.F. = $$ e^{-\log_e (x^{-5}+1)} $$ $\($ $\Rightarrow$ $\)$ I.F. = $$ (x^{-5} + 1)^{-1} = \frac{x^5}{x^5+1} $$ So, solution is given by $$ y \frac{x^5}{x^5+1} = \int \frac{x^5}{x^5+1} \times \frac{(x^5+1)^2}{x^7} dx $$ $\($ $\Rightarrow$ $\)$ $$ \frac{y x^5}{x^5+1} = \int \frac{x^5+1}{x^2} dx $$ $\($ $\Rightarrow$ $\)$ $$ \frac{y x^5}{x^5+1} = \int (x^3 + \frac{1}{x^2}) dx $$ $\($ $\Rightarrow$ $\)$ $$ \frac{y x^5}{x^5+1} = \frac{x^4}{4} - \frac{1}{x} + C $$ Since, $\($ y(1) = 2 $\)$, so $$ \frac{2}{2} = \frac{1}{4} - 1 + C \Rightarrow C = \frac{7}{4} $$ So, $$ \frac{y x^5}{x^5+1} = \frac{x^4}{4} - \frac{1}{x} + \frac{7}{4} $$ Put $\($ x = 2 $\)$, then we get $$ y(2) \times 32 = \frac{16}{4} - \frac{1}{2} + \frac{7}{4} $$ $$ \Rightarrow y(2) = \frac{33}{128} $$
Question 6
Maths · Vector Algebra · Single correct
If four distinct points with position vectors $\vec{a}$, $\vec{b}$, $\vec{c}$ and $\vec{d}$ are coplanar, then $$\begin{vmatrix} \vec{a} & \vec{b} & \vec{c} \end{vmatrix}$$ is equal to
If $f : \mathbb{R} \to \mathbb{R}$ be a continuous function satisfying $\int_{0}^{\frac{\pi}{2}} f(\sin 2x) \sin x \, dx + \alpha \int_{0}^{\frac{\pi}{4}} f(\cos 2x) \cos x \, dx = 0$, then the value of $\alpha$ is
$\sqrt{2}$
$-\sqrt{3}$
$\sqrt{3}$
$-\sqrt{2}$
Answer: (d)
Solution
Given, $$\int_0^{\frac{\pi}{2}} f(\sin 2x) \sin x \, dx + \alpha \int_0^{\frac{\pi}{4}} f(\cos 2x) \cos x \, dx = 0$$ Now, let $$I = \int_0^{\frac{\pi}{2}} f(\sin 2x) \cdot \sin x \, dx$$ Now using property $$\int_a^b f(x) \, dx = \int_a^c f(x) \, dx + \int_c^b f(x) \, dx$$ we get, $$\Rightarrow I = \int_0^{\frac{\pi}{4}} f(\sin 2x) \sin x \, dx + \int_{\frac{\pi}{4}}^{\frac{\pi}{2}} f(\sin 2x) \sin x \, dx$$ Now using property $$\int_a^b f(x) \, dx = \int_a^b f(a + b - x) \, dx$$ we get, $$\Rightarrow I = \int_0^{\frac{\pi}{4}} f(\cos 2x) \sin \left( \frac{\pi}{4} - x \right) \, dx + \int_0^{\frac{\pi}{4}} f(\cos 2x) \sin \left( \frac{\pi}{4} + x \right) \, dx$$ $$\Rightarrow I = \int_0^{\frac{\pi}{4}} f(\cos 2x) \left( \frac{1}{\sqrt{2}} \cos x - \frac{1}{\sqrt{2}} \sin x \right) \, dx + \int_0^{\frac{\pi}{4}} f(\cos 2x) \left( \frac{1}{\sqrt{2}} \cos x + \frac{1}{\sqrt{2}} \sin x \right) \, dx$$ $$\Rightarrow I = \int_0^{\frac{\pi}{4}} f(\cos 2x) \left( \sqrt{2} \cos x \right) \, dx$$ So, putting the value of $I$ in $$\int_0^{\frac{\pi}{2}} f(\sin 2x) \sin x \, dx + \alpha \int_0^{\frac{\pi}{4}} f(\cos 2x) \cos x \, dx = 0$$ we get, $$\alpha = -\sqrt{2}$$
Question 8
Maths · Determinants · Single correct
If the system of linear equations $$7x + 11y + \alpha z = 13$$ $$5x + 4y + 7z = \beta$$ $$175x + 194y + 57z = 361$$ has infinitely many solutions, then $\alpha + \beta + 2$ is equal to
The domain of the function $f(x) = \frac{1}{\sqrt{[x]^2 - 3[x] - 10}}$ is (where $[x]$ denotes the greatest integer less than or equal to $x$)
$(-\infty, -3] \cup (5, \infty)$
$(-\infty, -2) \cup [6, \infty)$
$(-\infty, -2) \cup (5, \infty)$
$(-\infty, -3] \cup [6, \infty)$
Answer: (b)
Solution
Given: $$f(x) = \frac{1}{\sqrt{[x]^2 - 3[x] - 10}}$$ For $f(x)$ to be defined, $$[x]^2 - 3[x] - 10 > 0$$ $$\Rightarrow ([x] - 5)([x] + 2) > 0$$ $$\Rightarrow [x] 5$$ $$\Rightarrow x < -2 and x \geq 6$$ So, domain is $(-\infty, -2) \cup [6, \infty)$.
Question 10
Maths · Three Dimensional Geometry · Single correct
Let $P$ be the plane passing through the points $(5, 3, 0), (13, 3, -2)$ and $(1, 6, 2)$. For $\alpha \in \mathbb{N}$, if the distance of the points $A(3, 4, \alpha)$ and $B(2, \alpha, a)$ from the plane $P$ are $2$ and $3$ respectively, then the positive value of $a$ is
6
3
5
4
Answer: (d)
Solution
Given, $P$ be the plane passing through the points $(5, 3, 0), (13, 3, -2)$ and $(1, 6, 2)$. Now, $\overrightarrow{AB} = 8\hat{i} - 2\hat{k}$, $\overrightarrow{AC} = -4\hat{i} + 3\hat{j} + 2\hat{k}$. So, normal vector to the plane will be, $$\overrightarrow{AB} \times \overrightarrow{AC} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 8 & 0 & -2 \\ -4 & 3 & 2 \end{vmatrix} = 6\hat{i} - 8\hat{j} + 24\hat{k}$$ Now equation of plane will be: $6x - 8y + 24z = d$. And given plane passes through $(5, 3, 0)$, so, $6 \times 5 - 8 \times 3 + 24 \times 0 = d \Rightarrow d = 6$. Hence, equation of plane will be, $$6x - 8y + 24z = 6 \Rightarrow 3x - 4y + 12z = 3$$ Now using the formula distance of point $(3, 4, \alpha)$ from the plane $3x - 4y + 12z = 3$, we get, $$\frac{9 - 16 + 12\alpha - 3}{\sqrt{9 + 16 + 144}} = 2 \Rightarrow \alpha = 3$$ Now again using the distance of point $(2, \alpha, a) = (2, 3, a)$ from the plane formula we get, $$\frac{3 \times 2 - 4 \times 3 + 12 \times a - 3}{13} = 3$$ $$\Rightarrow 12a - 9 = 39$$ $$\Rightarrow 12a = 48$$ $$\Rightarrow a = 4$$
Question 11
Maths · Mathematical Reasoning · Single correct
The converse of $((\sim p) \land q) \Rightarrow r$ is
$((\sim p) \lor q) \Rightarrow r$
$(\sim r) \Rightarrow p \land q$
$(\sim r) \Rightarrow ((\sim p) \land q)$
$(p \lor (\sim q)) \Rightarrow (\sim r)$
Answer: (d)
Solution
We know that, Converse of $A \Rightarrow B$ is $B \Rightarrow A$. So, using the above formula we get, Converse of $\sim p \land q \Rightarrow r$ $$\equiv r \Rightarrow (\sim p \land q)$$ $$\equiv (\sim r) \lor (\sim p \land q)$$ $$\equiv (\sim p \land q) \lor (\sim r)$$ $$\equiv \sim (p \lor \sim q) \lor (\sim r) \{ as \sim (A \lor B) \equiv \sim A \land \sim B \}$$ $$\equiv (p \lor (\sim q)) \Rightarrow (\sim r)$$
Question 12
Maths · Heights and Distances · Single correct
The angle of elevation of the top $P$ of a tower from the feet of one person standing due south of the tower is $45^\circ$ and from the feet of another person standing due west of the tower is $30^\circ$. If the height of the tower is $5$ meters, then the distance (in meters) between the two persons is equal to
$\frac{5}{2} \sqrt{5}$
10
5
5 $\sqrt{5}$
Answer: (b)
Solution
Given that the elevation to the top of the tower from the feet of one person due south is $45^\circ$. Similarly the angle of elevation to the top of tower from the feet of another person to the west of tower is $30^\circ$. The given information can be represented in the form of a diagram as below: We need to find the distance $AB$. Let the distance of $A, B$ from the tower be $x_1, x_2$. $$\Rightarrow \tan 45^\circ = \frac{5}{x_1}, \tan 30^\circ = \frac{5}{x_2}$$ $$\Rightarrow x_1 = 5, \; x_2 = 5\sqrt{3}.$$ $$\Rightarrow AB = \sqrt{x_1^2 + x_2^2} = \sqrt{(5)^2 + (5\sqrt{3})^2} = 10 \, \mathrm{m}$$ Hence this is the correct option.
Question 13
Maths · Sequences and Series · Single correct
Let $a$, $b$, $c$ and $d$ be positive real numbers such that $a + b + c + d = 11$. If the maximum value of $a^5b^3c^2d$ is $3750\beta$, then the value of $\beta$ is
If the radius of the largest circle with centre $(2, 0)$ inscribed in the ellipse $x^2 + 4y^2 = 36$ is $r$, then $12\, r^2$ is equal to
115
92
69
72
Answer: (b)
Solution
Given equation of ellipse is $\frac{x^2}{36} + \frac{y^2}{9} = 1$. It is of the form $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$ with $a = 6$, $b = 3$. The centre of the circle is $C(2, 0)$. Let $P(a \cos \theta, b \sin \theta)$ be the common point for ellipse and circle. $P \equiv (6 \cos \theta, 3 \sin \theta)$. Equation of normal to the ellipse will be $\frac{ax}{\cos \theta} - \frac{by}{\sin \theta} = a^2 - b^2$. $$\Rightarrow 6x \sec \theta - 3y \csc \theta = 36 - 9$$ But the normal through $P$ passes through the centre of the circle $C(2, 0)$. $$\Rightarrow 6(2) \sec \theta - 3(0) \csc \theta = 27$$ $$\Rightarrow \sec \theta = \frac{27}{12}$$ $$\Rightarrow \cos \theta = \frac{4}{9} and \sin \theta = \frac{\sqrt{65}}{9}$$ $$P \equiv \left( 6 \times \frac{4}{9}, 3 \times \frac{\sqrt{65}}{9} \right)$$ $$P \equiv \left( \frac{8}{3}, \frac{\sqrt{65}}{3} \right)$$ Now $CP = r = \sqrt{\left( 2 - \frac{8}{3} \right)^2 + \left( 0 - \frac{\sqrt{65}}{3} \right)^2}$. $$\Rightarrow r^2 = \frac{69}{9}$$ $$\Rightarrow 12r^2 = 12 \times \frac{69}{9} = 92$$ Therefore, the required answer is 92.
Question 15
Maths · Statistics · Single correct
Let the mean of 6 observations 1, 2, 4, 5, x and y be 5 and their variance be 10. Then their mean deviation about the mean is equal to
$\frac{7}{3}$
3
$\frac{8}{3}$
$\frac{10}{3}$
Answer: (c)
Solution
Consider the data 1, 2, 4, 5, x, y. So, Mean $$= \frac{1+2+4+5+x+y}{6}$$ $$\Rightarrow 5 = \frac{x+y+12}{6}$$ $$\Rightarrow x + y = 18$$ And, Variance $$= \left( \frac{\sum x_i^2}{n} \right) - \left( \frac{\sum x_i}{n} \right)^2$$ $$\Rightarrow 10 = \left( \frac{1^2+2^2+4^2+5^2+x^2+y^2}{6} \right) - (5)^2$$ $$\Rightarrow x^2 + y^2 = 164$$ We have $x + y = 18$ and $x^2 + y^2 = 164$. Now solving above equations we get, $x = 10$, $y = 8$. Now mean deviation about mean will be $$= \frac{|1-5| + |2-5| + |4-5| + |5-5| + |10-5| + |8-5|}{6}$$ $$= \frac{16}{6}$$ $$= \frac{8}{3}$$ Therefore, the required answer is $\frac{8}{3}$.
Question 16
Maths · Binomial Theorem · Single correct
The sum of the coefficients of three consecutive terms in the binomial expansion of $(1 + x)^{n+2}$, which are in the ratio $1 : 3 : 5$, is equal to
92
63
41
25
Answer: (b)
Solution
Ratio of three consecutive terms in the binomial expansion of $(1+x)^{n+2}$ is ${}^{n+2}C_{r-1} : {}^{n+2}C_{r} : {}^{n+2}C_{r+1} :: 1 : 3 : 5$. So, $$\frac{{}^{n+2}C_{r}}{{}^{n+2}C_{r-1}} = \frac{3}{1}$$ $$\Rightarrow \frac{n-r+3}{r} = 3$$ $$\Rightarrow n + 3 = 4r \ldots(1)$$ And, $$\frac{{}^{n+2}C_{r+1}}{{}^{n+2}C_{r}} = \frac{5}{3}$$ $$\Rightarrow \frac{n+2-r}{r+1} = \frac{5}{3}$$ $$\Rightarrow 3n + 6 - 3r = 5r + 5$$ $$\Rightarrow 3n + 1 = 8r \ldots(2)$$ So, $3(4r - 3) + 1 = 8r$ $$\Rightarrow 12r - 9 + 1 = 8r$$ $$\Rightarrow 4r = 8$$ $$\Rightarrow r = 2$$ So, $n = 5$. Hence, we have $$(1+x)^{n+2} = (1+x)^7$$ Sum of consecutive terms is $${}^{7}C_{1} + {}^{7}C_{2} + {}^{7}C_{3}$$ $$= 7 + 21 + 35 = 63$$
Question 17
Maths · Permutations and Combinations · Single correct
If the letters of the word MATHS are permuted and all possible words so formed are arranged as in a dictionary with serial numbers, then the serial number of the word THAMS is
103
102
101
104
Answer: (a)
Solution
The given word is MATHS. Arranging the letters alphabetically, we get AHMST. When the word starts with any of the letters A/H/M/S, the number of possibilities is $4! \times 4 = 96$. Now when the word starts with TA, then the number of possibilities is $3! = 6$. Now when the word starts with THAMS, then the number of possibilities is $1$. Rank $= 96 + 6 + 1 = 103$. Hence, rank of the word THAMS is 103.
Question 18
Maths · Complex Numbers and Quadratic Equations · Single correct
For $a \in \mathbb{C}$, let $A = \{ z \in \mathbb{C} : \mathrm{Re}(a + \bar{z}) > \mathrm{Im}(\bar{a} + z) \}$ and $B = \{ z \in \mathbb{C} : \mathrm{Re}(a + \bar{z}) 0$, then the set $A$ contains all the real numbers (S2) : If $\mathrm{Re}(a), \mathrm{Im}(a) < 0$, then the set $B$ contains all the real numbers,
Only (S2) is true
only (S1) is true
Both are true
Both are false
Answer: (d)
Solution
Let $a = x_1 + iy_1$, $\bar{a} = x_1 - iy_1$ and $z = x_2 + iy_2$, $\bar{z} = x_2 - iy_2$. Now, $$a + \bar{z} = (x_1 + x_2) + i(y_1 - y_2)$$ and $$\bar{a} + z = (x_1 + x_2) + i(y_2 - y_1)$$ Now according to the question, $$\mathrm{Re}(a + \bar{z}) = x_1 + x_2$$ and $$\mathrm{Im}(\bar{a} + z) = y_2 - y_1$$ $$A = \{ z : x_1 + x_2 > y_2 - y_1 \} = \{ z : x_1 + y_1 + x_2 > y_2 \}$$ $$B = \{ z : x_1 + x_2 0$ then $$A = \{ z : x_2 > -(x_1 + y_1) \}$$ $A$ covers a part of negative real axis and therefore, does not contain whole real axis. Similarly if $y_2 = 0$, and $x_1, y_1 < 0$, then $$B = \{ z : x_2 < -(x_1 + y_1) \}$$ $B$ covers part of positive real axis and therefore does not cover whole real axis. Hence, both are false.
Question 19
Maths · Relations and Functions · Single correct
Let $A = \{1, 3, 4, 6, 9\}$ and $B = \{2, 4, 5, 8, 10\}$. Let $R$ be a relation defined on $A \times B$ such that $R = \{(a_1, b_1), (a_2, b_2): a_1 \leq b_2$ and $b_1 \leq a_2\}$. Then the number of elements in the set $R$ is
160
52
26
180
Answer: (a)
Solution
Given, $A = \{1, 3, 4, 6, 9\}$ and $B = \{2, 4, 5, 8, 10\}$. And relation is given by, $$R = \{(a_1, b_1), (a_2, b_2): a_1 \leq b_2 and b_1 \leq a_2\}$$ Now taking cases for $a_1 \leq b_2$ we get, $a_1 = 1$, $b_2 \in \{2, 4, 5, 8, 10\} \rightarrow 5$ cases $a_1 = 3$, $b_2 \in \{4, 5, 8, 10\} \rightarrow 4$ cases $a_1 = 4$, $b_2 \in \{4, 5, 8, 10\} \rightarrow 4$ cases $a_1 = 6$, $b_2 \in \{8, 10\} \rightarrow 2$ cases $a_1 = 9$, $b_2 \in \{10\} \rightarrow 1$ cases So, total 16 cases will be there. Now finding cases of $b_1 \leq a_2$ we get, $b_1 = 2$, $a_2 \in \{3, 4, 6, 9\} \rightarrow 4$ cases $b_1 = 4$, $a_2 \in \{4, 6, 9\} \rightarrow 3$ cases $b_1 = 5$, $a_2 \in \{6, 9\} \rightarrow 2$ cases $b_1 = 8$, $a_2 \in \{9\} \rightarrow 1$ cases So, here total 10 cases. Hence, total elements in relation $= 16 \times 10 = 160$
Question 20
Maths · Continuity and Differentiability · Single correct
Let $f$ and $g$ be two functions defined by $f(x) = \begin{cases} x + 1, & x < 0 \\ |x - 1|, & x \geq 0 \end{cases}$ and $g(x) = \begin{cases} x + 1, & x < 0 \\ 1, & x \geq 0 \end{cases}$. Then $(g \circ f)(x)$ is
Continuous everywhere but not differentiable exactly at one point
Continuous everywhere but not differentiable at $x = 1$
Differentiable everywhere
Not continuous at $x = 1$
Answer: (a)
Solution
Given, $f(x) = x + 1,\quad x < 0$ $f(x) = |x - 1|,\quad x \geq 0$ and $g(x) = x + 1,\quad x < 0$ $g(x) = 1,\quad x \geq 0$ $( \Rightarrow f(x) = )$ $f(x) = x + 1,\quad x < 0$ $f(x) = 1 - x,\quad 0 \leq x < 1$ $f(x) = x - 1,\quad x \geq 1$ and $g(x) = 1 + x,\quad x < 0$ $g(x) = 1,\quad x \geq 0$ Now, for $( gof(x) )$ $gof(x) = 1 + f(x),\quad f(x) < 0,\; x < 0$ $gof(x) = 1,\quad f(x) \geq 0,\; x \geq 0$ $( \Rightarrow gof(x) = )$ $gof(x) = x + 2,\quad x < -1$ $gof(x) = 1,\quad x \geq -1$ Now plotting the diagram we get, Now from above diagram we can say that function is continuous but not differentiable at $( x = -1 )$ due to sharp corner.
Question 21
Maths · Complex Numbers and Quadratic Equations · Numerical
The number of points, where the curve $f(x) = e^{8x} - e^{6x} - 3e^{4x} - e^{2x} + 1$, $x \in \mathbb{R}$ cuts $x$-axis, is equal to..........
Answer: 2
Solution
Given, $$e^{8x} - e^{6x} - 3e^{4x} - e^{2x} + 1 = 0$$ $$\Rightarrow e^{4x} - e^{2x} - 3 - \frac{1}{e^{2x}} + \frac{1}{e^{4x}} = 0$$ $$\Rightarrow e^{4x} + \frac{1}{e^{4x}} + 2 - \left(e^{2x} + \frac{1}{e^{2x}}\right) = 5$$ $$\Rightarrow \left(e^{2x} + \frac{1}{e^{2x}}\right)^2 - \left(e^{2x} + \frac{1}{e^{2x}}\right) = 3$$ Now let $\left(e^{2x} + \frac{1}{e^{2x}}\right) = t$ So, the equation becomes $$t^2 - t - 5 = 0$$ $$\Rightarrow t = \frac{1 + \sqrt{21}}{2},$$ ignoring negative sign as exponential function are positive, Now $e^{2x} + \frac{1}{e^{2x}} = \frac{1 + \sqrt{21}}{2}$ $$\Rightarrow e^{4x} - \frac{1 + \sqrt{21}}{2} e^{2x} + 1 = 0$$ which is quadratic equation in $e^{2x}$ with upward parabola, Now by $A.M \geq G.M$ we get, $e^{2x} + \frac{1}{e^{2x}} \geq 2$ So, $y = \frac{1 + \sqrt{21}}{2} > 2$, hence it will cut at two distinct point, Hence, there will be two solution.
Question 22
Maths · Probability · Numerical
Let the probability of getting head for a biased coin be $\frac{1}{4}$. It is tossed repeatedly until a head appears. Let $N$ be the number of tosses required. If the probability that the equation $64x^2 + 5Nx + 1 = 0$ has no real root is $\frac{p}{q}$, where $p$ and $q$ are co-prime, then $q - p$ is equal to.........
Answer: 27
Solution
Given a quadratic equation $64x^2 + 5nx + 1 = 0$ has no real roots, so $D < 0$. $$\Rightarrow 25N^2 - 4 \times 64 < 0$$ $$\Rightarrow N < \frac{16}{5} \Rightarrow N = 1, 2, 3$$ And, for a biased coin, the probability of getting head is $P = \frac{1}{4}$, and probability of getting tail will be $Q = \frac{3}{4}$. So, required probability is $$\frac{1}{4} + \frac{3}{4} \cdot \frac{1}{4} + \left( \frac{3}{4} \right)^2 \cdot \frac{1}{4} + \left( \frac{3}{4} \right)^3 \cdot \frac{1}{4} = \frac{p}{q}$$ $$\Rightarrow \frac{1}{4} \left( 1 - \left( \frac{3}{4} \right)^3 \right) = \frac{p}{q}$$ $$\Rightarrow \frac{1}{1 - \left( \frac{3}{4} \right)} = \frac{p}{q}$$ $$\Rightarrow 1 - \left( \frac{3}{4} \right)^3 = \frac{p}{q}$$ $$\Rightarrow 1 - \frac{27}{64} = \frac{p}{q}$$ $$\Rightarrow \frac{p}{q} = \frac{37}{64}$$ $$q - p = 27$$
Question 23
Maths · Vector Algebra · Numerical
Let $\vec{a} = \hat{i} + 2\hat{j} + 3\hat{k}$ and $\vec{b} = \hat{i} + \hat{j} - \hat{k}$. If $\vec{c}$ is a vector such that $\vec{a} \cdot \vec{c} = 11$, $\vec{b} \cdot \left( \vec{a} \times \vec{c} \right) = 27$ and $\vec{b} \cdot \vec{c} = -\sqrt{3} \left| \vec{b} \right|$, then $\left| \vec{a} \times \vec{c} \right|^2$ is equal to
For $k \in \mathbb{N}$, if the sum of the series $1 + \frac{4}{k} + \frac{8}{k^2} + \frac{13}{k^3} + \frac{19}{k^4} + \ldots$ is $10$, then the value of $k$ is
Let $A = \{1, 2, 3, 4, 5\}$ and $B = \{1, 2, 3, 4, 5, 6\}$. Then the number of functions $f : A \to B$ satisfying $f(1) + f(2) = f(4) - 1$ is equal to...
Answer: 360
Solution
Given, $$f(1) + f(2) + 1 = f(4)$$ $$\Rightarrow f(1) + f(2) \leq 5 \{ as f(4) \leq 6 \}$$ Now taking cases we get, Case (1), $f(1) = 1 \Rightarrow f(2) = \{1, 2, 3, 4\} \rightarrow 4$ mappings Case (2), $f(1) = 2 \Rightarrow f(2) = \{1, 2, 3\} \rightarrow 3$ mappings Case (3), $f(1) = 3 \Rightarrow f(2) = \{1, 2\} \rightarrow 2$ mappings Case (4), $f(1) = 4 \Rightarrow f(2) = \{1\} \rightarrow 1$ mappings And $f(5)$ and $f(6) \rightarrow 6$ mapping each So, total number of function will be $=(4 + 3 + 2 + 1) \times 6 \times 6 = 360$
Question 27
Maths · Conic Sections · Numerical
Let the tangent to the parabola $y^2 = 12x$ at the point $(3, \alpha)$ be perpendicular to the line $2x + 2y = 3$. Then the square of distance of the point $(6, -4)$ from the normal to the hyperbola $\alpha^2 x^2 - 9y^2 = 9\alpha^2$ at its point $(\alpha - 1, \alpha + 2)$ is equal to ............
Answer: 116
Solution
Given, the tangent to the parabola $y^2 = 12x$ at the point $(3, \alpha)$ be perpendicular to the line $2x + 2y = 3$. So, Slope of tangent $= 1 = \frac{6}{\alpha} \Rightarrow \alpha = 6$. So, equation of hyperbola will be, $$36x^2 - 9y^2 = 324$$ $$\Rightarrow \frac{x^2}{9} - \frac{y^2}{36} = 1$$ Now equation of tangent at $(5, 8)$ will be, $$\frac{5x}{9} - \frac{8y}{36} = 1$$ $$\Rightarrow 5x - 2y = 9$$ So, slope of normal $= -\frac{2}{5}$. Now finding, equation of normal $y - 8 = -\frac{2}{5}(x - 5)$. $$\Rightarrow 5y - 40 = -2x + 10$$ $$\Rightarrow 5y + 2x = 50$$ Now finding, distance from $(6, -4)$, we get, $$= \frac{|12 - 20 - 50|}{\sqrt{29}} = \frac{58}{\sqrt{29}}$$ $$= 2\sqrt{29}$$ Hence, $$\left(2\sqrt{29}\right)^2 = 116$$
Question 28
Maths · Three Dimensional Geometry · Numerical
Let the line $L : x = \frac{1-y}{-2} = \frac{z-3}{\lambda}$, $\lambda \in \mathbb{R}$ meet the plane $P : x + 2y + 3z = 4$ at the point $(\alpha, \beta, \gamma)$. If the angle between the line $L$ and the plane $P$ is $\cos^{-1}\left(\sqrt{\frac{5}{14}}\right)$, then $\alpha + 2\beta + 6\gamma$ is equal to
Answer: 11
Solution
The given equations are, $$L: \frac{x-0}{1} = \frac{y-1}{2} = \frac{z-3}{\lambda} \& P: x + 2y + 3z = 4$$ So, Vector parallel to line: $$ = \vec{b}$$ Normal vector to plane $$P: = \vec{n}$$ Angle between plane and line is $\theta$. Then angle between the line and normal to the plane will be $90 - \theta$. Then, $$\Rightarrow \cos(90 - \theta) = \frac{(\hat{i} + 2\hat{j} + \lambda \hat{k}) \cdot (\hat{i} + 2\hat{j} + 3\hat{k})}{\sqrt{1^2 + 2^2 + \lambda^2} \cdot \sqrt{1^2 + 2^2 + 3^2}}$$ $$\Rightarrow \frac{3}{\sqrt{14}} = \frac{1 + 4 + 3\lambda}{\sqrt{\lambda^2 + 5} \sqrt{14}} \Rightarrow \lambda = \frac{2}{3}$$ $$L_1 = \frac{x-0}{3} = \frac{y-1}{6} = \frac{z-3}{2} = \mu$$ $$(x, y, z) \equiv (3\mu, 6\mu + 1, 2\mu + 3)$$ But this point lies on the plane: $$(3\mu + 12\mu + 2 + 6\mu + 9) = 4$$ $$\Rightarrow \mu = \frac{-1}{3}$$ Hence, $$\alpha = 3\mu = -1, \beta = 6\mu + 1 = -1, \gamma = 2\mu + 3 = \frac{7}{3}$$ Now, $$\alpha + 2\beta + 6\gamma = 11$$ Hence this is the required answer.
Question 29
Maths · Straight Lines and Pair of Straight Lines · Numerical
If the line $l_1 : 3y - 2x = 3$ is the angular bisector of the lines $l_2 : x - y + 1 = 0$ and $l_3 : \alpha x + \beta y + 17 = 0$, then $\alpha^2 + \beta^2 - \alpha - \beta$ is equal to ..........
Answer: 348
Solution
Given, $L_1 : 3y - 2x = 3$ is angular bisector of $L_2 : x - y + 1 = 0$ and $L_3 : \alpha x + \beta y + 17 = 0$ Now finding point of intersection of $L_1$ and $L_2$ we get, $(0, 1)$ And point will lie on $L_3$, so $\alpha \times 0 + \beta \times 1 + 17 = 0$ $$\Rightarrow \beta = -17$$ Any point, say $\left(-\frac{3}{2}, 0\right)$ on $L_1$ should be equidistant from lines $L_2$ and $L_3$ Now using the formula of distance of a point from the line we get, $$\Rightarrow \frac{\left|-\frac{3}{2} - 0 + 1\right|}{\sqrt{1^2 + 1^2}} = \frac{\left|-\frac{3\alpha}{2} - 0 + 17\right|}{\sqrt{\alpha^2 + (-17)^2}}$$ $$\Rightarrow (\alpha - 7)(\alpha - 17) = 0$$ Now, for $\alpha = 17$, $L_2$ and $L_3$ coincides So, $\alpha = 7$ Now putting the value of $\alpha$ and $\beta$ in given expression we get, $$\alpha^2 + \beta^2 - \alpha - \beta = (7^2) + (-17)^2 - 7 + 17 = 348$$
Question 30
Maths · Applications of Integrals · Numerical
If $A$ is the area in the first quadrant enclosed by the curve $C: 2x^2 - y + 1 = 0$, the tangent to $C$ at the point $(1, 3)$ and the line $x + y = 1$, then the value of $60A$ is..............
Answer: 16
Solution
Given, $y = 2x^2 + 1$ Now tangent to above equation at $(1, 3)$ is given by, $$y - 3 = 4(x - 1)$$ $$\Rightarrow y = 4x - 1$$ Now plotting the diagram we get, Required area of bounded region will be, $$A = \int_0^1 (2x^2 + 1) \, dx - area of \triangle QOT - area of \triangle PQR + area of \triangle QRS$$ $$\Rightarrow A = \left( \frac{2}{3} + 1 \right) - \frac{1}{2} - \frac{9}{8} + \frac{9}{40} = \frac{16}{40}$$ $$\Rightarrow 60A = 16$$
Physics
Question 31
Physics · Mechanical Properties of Fluids · Single correct
Eight equal drops of water are falling through air with a steady speed of $10 \, \mathrm{cm} \, \mathrm{s}^{-1}$. If the drops coalesce, the new velocity is:-
$16 \, \mathrm{cm} \, \mathrm{s}^{-1}$
$40 \, \mathrm{cm} \, \mathrm{s}^{-1}$
$5 \, \mathrm{cm} \, \mathrm{s}^{-1}$
$10 \, \mathrm{cm} \, \mathrm{s}^{-1}$
Answer: (b)
Solution
The terminal velocity can be given by $$v_T = \frac{2(\rho - \sigma) r^2 g}{9 \eta}.$$ Clearly, $v_T \propto r^2$. Let the radius of the small drops be $r_1$ and the radius of the big drop be $r_2$. So, $$8 \left( \frac{4\pi}{3} \right) r_1^3 = \left( \frac{4\pi}{3} \right) r_2^3$$ $$\Rightarrow r_1 = \frac{r_2}{2}$$ Hence, taking the ratio $$\left( \frac{v_T}{v_T} \right)_1 = \left( \frac{r_1}{r_2} \right)^2$$ $$\Rightarrow \frac{10}{(v_T)_2} = \frac{1}{4}$$ $$\Rightarrow (v_T)_2 = 40 \, \mathrm{cm} \, \mathrm{s}^{-1}$$
Question 32
Physics · Waves · Single correct
A car $P$ travelling at $20 \, \mathrm{m} \, \mathrm{s}^{-1}$ sounds its horn at a frequency of $400 \, \mathrm{Hz}$. Another car $Q$ is travelling behind the first car in the same direction with a velocity $40 \, \mathrm{m} \, \mathrm{s}^{-1}$. The frequency heard by the passenger of the car $Q$ is approximately [Take, velocity of sound = $360 \, \mathrm{m} \, \mathrm{s}^{-1}$]
$421 \, \mathrm{Hz}$
$471 \, \mathrm{Hz}$
$485 \, \mathrm{Hz}$
$514 \, \mathrm{Hz}$
Answer: (b)
Solution
Let velocity of sound in air be $v \, \mathrm{m \, s^{-1}}$. Using Doppler formula, $$f = f_0 \left( \frac{v + v_0}{v - v_s} \right)$$ $$= f_0 \left( \frac{v + 40}{v - 20} \right)$$ $$= 400 \left( \frac{360 + 40}{340} \right)$$ $$\approx 471 \, \mathrm{Hz}$$
Question 33
Physics · Electromagnetic Waves · Single correct
A plane electromagnetic wave of frequency $20 \, \mathrm{MHz}$ propagates in free space along x-direction. At a particular space and time $\vec{E} = 6.6 \hat{j} \, \mathrm{V \, m^{-1}}$. What is $\vec{B}$ at this point?
$2.2 \times 10^{-8} \hat{k} \, \mathrm{T}$
$-2.2 \times 10^{-8} \hat{i} \, \mathrm{T}$
$-2.2 \times 10^{-8} \hat{k} \, \mathrm{T}$
$2.2 \times 10^{-8} \hat{i} \, \mathrm{T}$
Answer: (a)
Solution
It is given that $\vec{E} = 6.6 \hat{j} \left( \mathrm{V \, m^{-1}} \right)$. The relation between the electric, magnetic field and speed of light is $\vec{E} \times \vec{B} = \vec{c}$. Clearly, $\vec{B} = B_0 \left( \hat{k} \right)$. Using the relation, $cB_0 = E$. Therefore, $$B_0 = \left( \frac{E}{c} \right) = \frac{6.6}{3 \times 10^8} = 2.2 \times 10^{-8} \, \mathrm{T}$$
Question 34
Physics · Electrostatic Potential and Capacitance · Single correct
A capacitor of capacitance $C$ is charged to a potential $V$. The flux of the electric field through a closed surface enclosing the positive plate of the capacitor is:
$\frac{CV}{\varepsilon_0}$
Zero
$\frac{2CV}{\varepsilon_0}$
$\frac{CV}{2\varepsilon_0}$
Answer: (a)
Solution
The charge enclosed is given by $q_{inc} = CV$. Gauss' law states that the flux through any closed surface is equal to the charge enclosed by the surface. Using Gauss' law the flux is, $$\phi = \frac{q_{inc}}{\varepsilon_0} = \left( \frac{CV}{\varepsilon_0} \right)$$
Question 35
Physics · Physical World, Units and Measurements · Single correct
If force $(F)$, velocity $(V)$ and time $(T)$ are considered as fundamental physical quantity, then dimensional formula of density will be :
$F \, V^4 \, T^{-6}$
$F \, V^{-4} \, T^{-2}$
$F^2 \, V^{-2} \, T^6$
$F \, V^{-2} \, T^2$
Answer: (b)
Solution
The dimensional formula of force is $F = MLT^{-2}$. The dimensional formula of velocity is $V = LT^{-1}$. The formula for density is $$Density = \frac{M}{L^3} = ML^{-3}$$ Comparing the density dimensions with the assumed fundamental quantities in the question, $$ML^{-3} = [F]^x [V]^y [T]^z$$ $$\Rightarrow ML^{-3} = [MLT^{-2}]^x [LT^{-1}]^y [T]^z$$ $$\Rightarrow ML^{-3} = M^x L^{(x+y)} T^{-2x-y+z}$$ Comparing the exponents, $$x = 1 \cdots (i)$$ $$x + y = -3 \cdots (ii)$$ $$-2x - y + z = 0 \cdots (iii)$$ Solving equations (i), (ii) $\&$ (iii), we get $y = -4$, $z = -2$. The dimension is derived as $F V^{-4} T^{-2}$.
Question 36
Physics · Communication Systems · Single correct
In satellite communication, the uplink frequency band used is:
$420 - 890$ $\mathrm{MHz}$
$5.925 - 6.425$ $\mathrm{GHz}$
$76 - 88$ $\mathrm{MHz}$
$3.7 - 4.2$ $\mathrm{GHz}$
Answer: (b)
Solution
In satellite telecommunication, a downlink is the link from a satellite down to one or more ground stations or receivers, and an uplink is the link from a ground station up to a satellite. Uplink frequency band for satellite communication is $5.925 - 6.425 \, \mathrm{GHz}$.
Question 37
Physics · Electric Charges and Fields · Single correct
If $V$ is the gravitational potential due to sphere of uniform density on its surface, then its value at the centre of sphere will be:
$\frac{4}{3} V$
$\frac{V}{2}$
$V$
$\frac{3V}{2}$
Answer: (d)
Solution
The magnitude of gravitational potential of a solid sphere at a distance $r$ from the centre is $$V = \frac{-GM}{2R^3} \left( 3R^2 - r^2 \right)$$ At $r = R$, $V = \frac{-GM}{R}$. At $r = 0$, $V' = \frac{-GM}{2R^3} \left( 3R^2 \right) = \frac{-3GM}{2R}$. Clearly, $V' = \frac{3V}{2}$.
Question 38
Physics · Laws of Motion · Single correct
A body of mass 500 g moves along x-axis such that it's velocity varies with displacement x according to the relation $v = 10\sqrt{x} \, \mathrm{m} \, \mathrm{s}^{-1}$ the force acting on the body is:
125 N
25 N
166 N
5 N
Answer: (b)
Solution
It is given that $v = 10 \sqrt{x} \, \mathrm{m \, s^{-1}}$ Force is defined by $F = m \frac{dv}{dt} \cdots (i)$ Multiplying and dividing equation (i) by $dx$ $$F = m \frac{dv}{dt} \frac{dx}{dx}$$ $$\Rightarrow F = m \frac{dx}{dt} \frac{dv}{dx} = mv \frac{dv}{dx} \cdots (ii)$$ Finding the values of the terms in equation (ii) $$\frac{dv}{dx} = \frac{10}{2\sqrt{x}} = \frac{5}{\sqrt{x}}$$ $$v \frac{dv}{dx} = a = 10 \sqrt{x} \times \frac{5}{\sqrt{x}} = 50 \, \mathrm{m \, s^{-2}}$$ Hence, the force is $$F = \frac{1}{2} \times 50 = 25 \, \mathrm{N}.$$
Question 39
Physics · Motion in a Plane · Single correct
A projectile is projected at $30^\circ$ from horizontal with initial velocity 40 $\mathrm{m \, s^{-1}}$. The velocity of the projectile at t = 2 $\mathrm{s}$ from the start will be: (Given g = 10 $m/s^2$)
$40\sqrt{3} \, \mathrm{m \, s^{-1}}$
Zero
$20 \, \mathrm{m \, s^{-1}}$
$20\sqrt{3} \, \mathrm{m \, s^{-1}}$
Answer: (d)
Solution
It is given that $v = 40 \, \mathrm{m \, s^{-1}}$. The components of the velocity will be $$v_y = v \sin 30^\circ = \frac{40 \, \mathrm{m \, s^{-1}}}{2} = 20 \, \mathrm{m \, s^{-1}}$$ $$v_x = v \cos 30^\circ = \frac{40 \sqrt{3}}{2} \, \mathrm{m \, s^{-1}} = 20 \sqrt{3} \, \mathrm{m \, s^{-1}}$$ The time taken to reach maximum height is $T = \frac{u \sin 30^\circ}{g} = \frac{20 \, \mathrm{m \, s^{-1}}}{10 \, \mathrm{m \, s^{-2}}} = 2 \, \mathrm{s}$. Hence, at $T = 2 \, \mathrm{s}$, as $v_y = 0 \, \mathrm{m \, s^{-1}}$ therefore $v_{net} = v_x = 20 \sqrt{3} \, \mathrm{m \, s^{-1}}$.
Question 40
Physics · Ray Optics and Optical Instruments · Single correct
When one light ray is reflected from a plane mirror with $30^\circ$ angle of reflection, the angle of deviation of the ray after reflection is:
120^$\circ$
110^$\circ$
140^$\circ$
130^$\circ$
Answer: (a)
Solution
It is given that $i = 30^\circ$. The formula for angle of deviation is $$\delta = 180^\circ - 2i$$ Substituting the values, $$\delta = 180^\circ - 60^\circ$$ $$= 120^\circ$$
Question 41
Physics · Gravitation · Single correct
A space ship of mass $2 \times 10^4 \, \mathrm{kg}$ is launched into a circular orbit close to the earth surface. The additional velocity to be imparted to the space ship in the orbit to overcome the gravitational pull will be (if $g = 10 \, \mathrm{m \, s^{-2}}$ and radius of earth $= 6400 \, \mathrm{km}$):
The orbital velocity of satellite is $$v_{orb} = \sqrt{\frac{GM}{R}}$$ The escape velocity is $$v_{esc} = \sqrt{\frac{2GM}{R}}$$ Hence, the additional velocity required is $$\Delta v = v_{esc} - v_{orb} = \sqrt{\frac{2GM}{R}} - \sqrt{\frac{GM}{R}} = \left(\sqrt{2} - 1\right) \sqrt{\frac{GM}{R}}$$ $$= \left(\sqrt{2} - 1\right) \sqrt{gR}$$ $$= \left(\sqrt{2} - 1\right) \sqrt{10 \times 6400 \times 10^3}$$ $$= 8 \left(\sqrt{2} - 1\right) \, km \, s^{-1}$$
Question 42
Physics · Dual Nature of Radiation and Matter · Single correct
The ratio of the de-Broglie wavelengths of proton and electron having same kinetic energy: (Assume $m_p = m_e \times 1849$)
1 : 43
1 : 30
1 : 62
2 : 43
Answer: (a)
Solution
The de-Broglie wavelength is given by $$\lambda = \frac{h}{p} = \frac{h}{\sqrt{2mK}} \left( As, p^2 = 2mK \right).$$ It is given that $$(K)_e = (K)_p$$ Thus, the ratio of the wavelengths of the proton and electron is $$\frac{\lambda_p}{\lambda_e} = \frac{\sqrt{2K m_e}}{\sqrt{2K m_p}} = \sqrt{\frac{m_e}{m_p}} = \sqrt{\frac{1}{1849}} = \frac{1}{43}.$$
Question 43
Physics · Thermodynamics · Single correct
The thermodynamic process, in which internal energy of the system remains constant is
Isochoric
Adiabatic
Isothermal
Isobaric
Answer: (c)
Solution
An isothermal process is a thermodynamic process in which the temperature of a system remains constant. The transfer of heat into or out of the system happens so slowly that thermal equilibrium is maintained. $$\Delta T = 0, \Delta U = nC_V \Delta T = 0.$$ According to the first law of thermodynamics, $$\Delta Q = \Delta U + \Delta W$$ $$\Rightarrow \Delta Q = \Delta W$$
Question 44
Physics · Atoms · Single correct
The energy of $\mathrm{He}^+$ ion in its first state is, (The ground state energy for the Hydrogen atom $-13.6 \, \mathrm{eV}$):
$-27.2 \, \mathrm{eV}$
$-3.4 \, \mathrm{eV}$
$-13.6 \, \mathrm{eV}$
$-54.4 \, \mathrm{eV}$
Answer: (c)
Solution
Energy of Hydrogen like atoms is, $E = \frac{-13.6Z^2}{n^2} eV$. Since Helium is in the first state, $Z = 2$, $n = 2$. The energy of $\mathrm{He}^+$ ion is, $$E = \frac{-13.6 \times 2^2}{2^2} = -13.6 eV$$
Question 45
Physics · Semiconductor Electronics: Materials, Devices and Simple Circuits · Single correct
The logic operations performed by the given digital circuit is equivalent to:
NOR
AND
OR
NAND
Answer: (b)
Solution
As shown in the figure the various logic gates have been mentioned. Let the output before the NOT gate be $Z$. Using the expression for the logic gates, it can be written $$Z = \overline{(A + B)} \cdot (A \cdot B)$$ Hence, the output $Y$ is $$Y = \overline{Z} = \overline{(A + B) \cdot (A \cdot B)}$$ $$\Rightarrow Y = A \cdot B$$ Hence the digital circuit is equivalent to an AND gate.
Question 46
Physics · Kinetic Theory · Single correct
The root mean square speed of molecules of nitrogen gas at 27°C is approximately: (Given mass of a nitrogen molecule = $4.6 \times 10^{-26}$ kg and take Boltzmann constant $k_B = 1.4 \times 10^{-23}$ J K$^{-1}$)
$27.4\ \mathrm{m\,s^{-1}}$
$91\ \mathrm{m\,s^{-1}}$
$1260\ \mathrm{m\,s^{-1}}$
$523\ \mathrm{m\,s^{-1}}$
Answer: (d)
Solution
The RMS value of a gas is given by $$v_{rms} = \sqrt{\frac{3RT}{M}}$$ $$= \sqrt{\frac{3k_B T}{m}}$$ Substituting the given values, $$v_{rms} = \sqrt{\frac{3 \times 1.4 \times 10^{-23} \times 300}{4.6 \times 10^{-26}}}$$ $$\approx 523 \, \mathrm{m \, s^{-1}}$$
Question 47
Physics · Current Electricity · Single correct
The current flowing through $R_2$ is :
$\frac{2}{3}$ A
$\frac{1}{2}$ A
$\frac{1}{3}$ A
$\frac{1}{4}$ A
Answer: (c)
Solution
As can be seen from the first circuit above, $CB$ and $AB$ are in series which is in parallel with $CA$. So, the net resistance is $R' = \frac{6}{2} \, \Omega = 3 \, \Omega$ as shown in the second diagram. From the second diagram, $DC$ and $CA$ is in series which is parallel to $DA$. Hence the resistance is $$R'' = \left( \frac{6 \times 3}{6 + 3} \right) \, \Omega = 2 \, \Omega$$ as shown in the third diagram. From the third diagram, both $ED$ and $DA$ are in series which is parallel to $EA$. The equivalent resistance as can be seen from the above simplified circuit is $R_{eq} = 2 \, \Omega$. The current $I$ through battery, $I = \frac{8}{2} = 4 \, \mathrm{A}$. From the second diagram, the part $EDACD$ has a resistance of $4 \, \Omega$, the total current will divide equally between $EDACD$ and $EA$. So consider $I_1 = 2 \, \mathrm{A}$ flowing through $ED$. Note that $I_1$ will be the same current flowing in the first diagram through $ED$. From the first diagram, when the resistances are in parallel the current is divided in the inverse ratio. Thus, $I'$ through $CB = \frac{2}{3} \times 2 = \frac{4}{3} \, \mathrm{A}$ $I''$ through $R_2 = \frac{1}{2} \left( \frac{2}{3} \right) = \frac{1}{3} \, \mathrm{A}$
Question 48
Physics · Mathematics in Physics · Single correct
When vector $\vec{A} = 2\hat{i} + 3\hat{j} + 2\hat{k}$ is subtracted from vector $\vec{B}$, it gives a vector equal to $2\hat{j}$. Then the magnitude of vector $\vec{B}$ will be:
$\sqrt{5}$
3
$\sqrt{6}$
$\sqrt{33}$
Answer: (d)
Solution
It is given that $\vec{A} = 2\hat{i} + 3\hat{j} + 2\hat{k}$. By the given condition, $$\vec{B} - \left(2\hat{i} + 3\hat{j} + 2\hat{k}\right) = 2\hat{j}$$ $$\Rightarrow \vec{B} = 2\hat{i} + 5\hat{j} + 2\hat{k}$$ The magnitude is given by the formula, $$\left| \vec{B} \right| = \sqrt{B_x^2 + B_y^2 + B_z^2}$$ $$\Rightarrow \left| \vec{B} \right| = \sqrt{4 + 25 + 4} = \sqrt{33}$$
Question 49
Physics · Magnetism and Matter · Single correct
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: A bar magnet dropped through a metallic cylindrical pipe takes more time to come down compared to a non-magnetic bar with same geometry and mass. Reason R: For the magnetic bar, Eddy currents are produced in the metallic pipe which oppose the motion of the magnetic bar. In the light of the above statements, choose the correct answer from the options given below
A is false but R is true
Both A and R are true and R is the correct explanation of A
A is true but R is false
Both A and R are true and R is NOT the correct explanation of A
Answer: (b)
Solution
Due to change in flux, eddy current is produced which opposes the motion in the metallic pipe for the bar magnet. Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. Hence, R is the correct explanation and both statements are true.
Question 50
Physics · Moving Charges and Magnetism · Single correct
An electron is allowed to move with constant velocity along the axis of current carrying straight solenoid. (A). The electron will experience magnetic force along the axis of the solenoid. (B). The electron will not experience magnetic force. (C). The electron will continue to move along the axis of the solenoid. (D). The electron will be accelerated along the axis of the solenoid. (E). The electron will follow parabolic path-inside the solenoid. Choose the correct answer from the option given below:
B, C and D only
A and D only
B and C only
B and E only
Answer: (c)
Solution
The Lorentz force is given by $\vec{F} = q \left( \vec{v} \times \vec{B} \right) = qvB \sin \theta \hat{n}$. The angle $\theta = 0^\circ$. Hence the force experienced is zero. Thus, the electron will not experience any magnetic force and the electron will continue to move along the axis.
Question 51
Physics · Electrostatic Potential and Capacitance · Numerical
In the given circuit. $C_1 = 2\,\mu F$, $C_2 = 0.2\,\mu F$, $C_3 = 2\,\mu F$, $C_4 = 4\,\mu F$, $C_5 = 2\,\mu F$, $C_6 = 2\,\mu F$. The charge stored on capacitor $C_4$ is $\mu C$.
Answer: 4
Solution
From the diagram of the circuit, $C_3$, $C_4$, $C_5$ are in series, so the total capacitance is $$\frac{1}{C'} = \frac{1}{2} + \frac{1}{4} + \frac{1}{2}$$ $$\Rightarrow C' = \frac{4}{5} \, \mu F$$ $C'$ and $C_2$ are parallel, the total capacitance is $$C'' = \left( \frac{4}{5} + 0.2 \right) \, \mu F = 1 \, \mu F$$ $C_1$, $C''$, $C_6$ are in series. So the equivalent capacitance is, $$\frac{1}{C_{eq}} = \frac{1}{2} + 1 + \frac{1}{2}$$ $$\Rightarrow C_{eq} = 0.5 \, \mu F$$ Using $Q = C_{eq} V$. The charge through the battery, $Q = 10 \times \frac{1}{2} = 5 \, \mu C$ From the diagram above, $$Q' = \frac{5 \, \mu C \times 0.8}{0.8 + 0.2} = 4 \, \mu C$$
Question 52
Physics · System of Particles and Rotational Motion · Numerical
A circular plate is rotating in horizontal plane, about an axis passing through its centre and perpendicular to the plate, with an angular velocity $\omega$. A person sits at the centre having two dumbbells in his hands. When he stretched out his hands, the moment of inertia of the system becomes triple. If $E$ be the initial Kinetic energy of the system, then final Kinetic energy will be $\frac{E}{x}$. The value of $x$ is
Answer: 3
Solution
The kinetic energy is given by $$E = \frac{1}{2} I \omega^2 = \left( \frac{L^2}{2I} \right)$$ It is given that the new moment of inertia $$I' = 3I$$ Clearly, the final kinetic energy is $$E_f = \frac{L^2}{2I'} = \frac{L^2}{6I}$$ $$\Rightarrow E_f = \left( \frac{E}{3} \right)$$
Question 53
Physics · Nuclei · Fill in the blank
A nucleus disintegrates into two nuclear parts, in such a way that ratio of their nuclear sizes is $1 : 2^{1/3}$. Their respective speed have a ratio of $n : 1$. The value of n is________
Answer: 2
Solution
Using the law of Momentum conservation $$m_1 v_1 + m_2 (-v_2) = 0$$ Thus, $$m_1 v_1 = m_2 v_2$$ Therefore, $$\left( \frac{m_1}{m_2} \right) = \left( \frac{v_2}{v_1} \right)$$ Substituting, $$\frac{4 \pi r_1^3}{3} = \frac{4 \pi r_2^3}{3}$$ Thus, $$\left( \frac{r_1}{r_2} \right)^3 = \left( \frac{v_2}{v_1} \right)$$ It is given $$\frac{r_1}{r_2} = \frac{1}{2^{\frac{1}{3}}}$$ and $$\left( \frac{r_1}{r_2} \right)^3 = \left( \frac{v_2}{v_1} \right)$$ Therefore, $$\left( \frac{1}{2} \right) = \left( \frac{v_2}{v_1} \right)$$ Thus, $$\frac{v_1}{v_2} = \frac{2}{1}$$
Question 54
Physics · Current Electricity · Numerical
Two identical cells each of emf 1.5 V are connected in series across a 10 $\Omega$ resistance. An ideal voltmeter connected across 10 $\Omega$ resistance reads 1.5 V. The internal resistance of each cell is _____ $\Omega$.
A block of mass 5 kg starting from rest pulled up on a smooth incline plane making an angle of $30^\circ$ with horizontal with an effective acceleration of $1 \, \mathrm{m} \, \mathrm{s}^{-2}$. The power delivered by the pulling force at $t = 10 \, \mathrm{s}$ from the start is _____ W. [Use $g = 10 \, \mathrm{m} \, \mathrm{s}^{-2}$] (Calculate the nearest integer value)
Answer: 300
Solution
Let's consider the following free-body diagram: From the above diagram, it can be written that $$F - mg \sin 30^\circ = ma \ldots (1)$$ Substitute the values of the known parameters into equation (1) and solve to calculate the force applied on the block. $$F - 50 \sin 30^\circ = 5 \times 1$$ $$\Rightarrow F = (5 + 25) \, \mathrm{N}$$ $$= 30 \, \mathrm{N}$$ The velocity of the block $(v)$ at $t = 10 \, \mathrm{s}$ can be written as $$v = 0 + 1 \, \mathrm{m/s^2} \times 10 \, \mathrm{s}$$ $$= 10 \, \mathrm{m/s}$$ Hence, the required power is given by $$P = Fv$$ $$= 30 \, \mathrm{N} \times 10 \, \mathrm{m/s}$$ $$= 300 \, \mathrm{W}$$
Question 56
Physics · Electromagnetic Induction · Numerical
A coil has an inductance of 2 $\mathrm{H}$ and resistance of 4 $\Omega$. A 10 $\mathrm{V}$ is applied across the coil. The energy stored in the magnetic field after the current has built up to its equilibrium value will be _____ $\times 10^{-2}$ $\mathrm{J}$
Answer: 625
Solution
The data given is $L = 2 \, \mathrm{H}$ $R = 4 \, \Omega$ $V = 10 \, \mathrm{V}$ Using Ohm's law, $V = IR$, $$I = \frac{10 \, \mathrm{V}}{4 \, \Omega} = \frac{5}{2} \, \mathrm{A}$$ The energy of an inductor is given by $$E = \frac{1}{2} LI^2 = \frac{1}{2} \times 2 \times \left( \frac{25}{4} \right) = 625 \times 10^{-2} \, \mathrm{J}$$
Question 57
Physics · Electromagnetic Induction · Numerical
A metallic cube of side 15 cm moving along $y$-axis at a uniform velocity of $2 \, \mathrm{m} \, \mathrm{s}^{-1}$. In a region of uniform magnetic field of magnitude $0.5 \, \mathrm{T}$ directed along $z$-axis. In equilibrium the potential difference between the faces of higher and lower potential developed because of the motion through the field will be mV.
Answer: 150
Solution
Using the equation $$qE = qvB$$ $$\Rightarrow E = vB$$ Using the relation $\Delta V = Ed$ $$\Rightarrow \Delta V = vBd$$ $$= 2 \times \frac{1}{2} \times 0.15 \, \mathrm{V}$$ $$= 0.15 \, \mathrm{V} = 150 \, \mathrm{mV}$$
Question 58
Physics · Waves · Numerical
A wire of density $8 \times 10^3 \, \mathrm{kg \, m^{-3}}$ is stretched between two clamps $0.5 \, \mathrm{m}$ apart. The extension developed in the wire is $3.2 \times 10^{-4} \, \mathrm{m}$. If $Y = 8 \times 10^{10} \, \mathrm{N \, m^{-2}}$, the fundamental frequency of vibration in the wire will be _____ Hz
Answer: 80
Solution
Using the relation of Young's modulus, $$\frac{T}{A} = Y \left( \frac{\Delta L}{L} \right)$$ which implies $$T = \left( \frac{Y \Delta L}{L} \times A \right).$$ The linear mass density is $$\mu = \left( \frac{m}{L} \right).$$ So, $$\frac{T}{\mu} = \frac{Y \Delta L A}{L \left( \frac{m}{L} \right)} = \frac{Y (\Delta L) \times L A}{L (m)} = \left( \frac{Y \Delta L}{L} \right) \times \left( \frac{1}{\rho} \right).$$ Substituting the values, $$\frac{T}{\mu} = \frac{8 \times 10^{10} \times 3.2 \times 10^{-4}}{0.5} \times \left( \frac{1}{8 \times 10^3} \right) = 6.4 \times 10^3$$ which implies $$\frac{T}{\mu} = 64 \times 10^2.$$ The fundamental frequency is given by $$f = \frac{1}{2L} \sqrt{\frac{T}{\mu}}.$$ Therefore, $$\sqrt{\frac{T}{\mu}} = 8 \times 10 = 80 \, \mathrm{m \, s^{-1}}.$$ Therefore, $$f = \left( \frac{80}{1} \right) = 80 \, \mathrm{Hz}.$$
Question 59
Physics · Mechanical Properties of Fluids · Numerical
The surface tension of soap solution is $3.5 \times 10^{-2} \, \mathrm{N \, m^{-1}}$. The amount of work done required to increase the radius of soap bubble from $10 \, \mathrm{cm}$ to $20 \, \mathrm{cm}$ is _____ $\times 10^{-4} \, \mathrm{J}$. (take $\pi = \frac{22}{7}$)
Answer: 264
Solution
The amount of work done is equal to the change in the surface energy to increase the radius of the bubble. The formula to calculate the change in surface energy is given by $$\Delta U = 2(T \times \Delta A) \ldots (1)$$ Substitute the values of the known parameters into equation (1) to calculate the required work done. $$\Delta U = 3.5 \times 10^{-2} \times 4 \pi \left[ (0.2)^2 - (0.1)^2 \right] \times 2 \, \mathrm{J}$$ $$= 3.5 \times 10^{-2} \times 4 \times \frac{22}{7} \times 0.03 \times 2$$ $$= 2 \times 1.32 \times 10^{-2}$$ $$= 264 \times 10^{-4} \, \mathrm{J}$$
Question 60
Physics · Ray Optics and Optical Instruments · Numerical
As shown in the figure, a plane mirror is fixed at a height of $50$ cm from the bottom of tank containing water $\left( \mu = \frac{4}{3} \right)$. The height of water in the tank is $8$ cm. A small bulb is placed at the bottom of the water tank. The distance of image of the bulb formed by mirror from the bottom of the tank is ______ cm.
Answer: 98
Solution
The data given is $d = 8 \, \mathrm{cm}$ $\mu = \frac{4}{3}$ Apparent depth is $$h' = \frac{d}{\mu} = \frac{8}{\frac{4}{3}} = 6 \, \mathrm{cm}$$ Distance of object from mirror $= 42 + 6 = 48 \, \mathrm{m}$ Distance of image from bottom of tank $= 48 + 50 = 98 \, \mathrm{m}$
Chemistry
Question 61
Chemistry · Hydrogen · Single correct
Which hydride among the following is less stable?
BeH_2
HF
NH_3
LiH
Answer: (a)
Solution
BeH$_2$ is indeed considered to be less stable compared to other hydrides among the given due to its significant covalent character and electron deficiency. Beryllium, being a small and highly charged cation, attracts the electrons in the Be–H bonds more strongly, resulting in a greater degree of electron sharing between beryllium and hydrogen. This covalent character is in contrast to other alkaline earth metal hydrides, which tend to have more ionic character.
Question 62
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
Given below are two statements, one is labelled as Assertion $\textbf{A}$ and the other is labelled as Reason $\textbf{R}$.
$\textbf{A}$ is true but $\textbf{R}$ is false
$\textbf{A}$ is false but $\textbf{R}$ is true
Both $\textbf{A}$ and $\textbf{R}$ are true and $\textbf{R}$ is the correct explanation of $\textbf{A}$
Both $\textbf{A}$ and $\textbf{R}$ are true and $\textbf{R}$ is NOT the correct explanation of $\textbf{A}$
Answer: (b)
Solution
The reagent hydrazine in alkaline medium is used in the Wolff-Kishner reduction reaction. In this reaction aldehydes and ketone converts to respective alkanes. This reaction is not good for base sensitive groups in the carbonyl compounds. The following chloro carbonyl compound gives alkene as elimination reaction expected in the presence of base.
Question 63
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
The major product formed in the following reaction is Choose the correct answer from the options given below:
B only
A only
C only
D only
Answer: (b)
Solution
The carbonyl compounds undergo Clemmensen's reduction in the presence of zinc amalgam and concentrated hydrochloric acid to form alkanes. The reagent in the Clemmensen reduction is not compatible with acid-sensitive functional groups. In the given reactant, the hydroxy group undergoes dehydration to give alkene as shown below.
Question 64
Chemistry · Haloalkanes and Haloarenes · Single correct
Which of the following compounds is an example of Freon?
$\mathrm{C_2H_2F_2}$
$\mathrm{C_2F_4}$
$\mathrm{C_2HF_3}$
$\mathrm{C_2Cl_2F_2}$
Answer: (d)
Solution
$\mathrm{C_2Cl_2F_2}$ is an example of freon. It can act as an aerosol propellant, refrigerant, or organic solvent because it is a gas at room temperature and a liquid when cooled or compressed. Freon is a term that was commonly used to refer to a group of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) compounds.
Question 65
Chemistry · Chemical Kinetics and Nuclear Chemistry · Single correct
What is the value of $x$ and $y$?
160 and 4
80 and 4
80 and 2
40 and 4
Answer: (c)
Solution
To determine the values of $x$ and $y$, we can use the information provided and the rate expression for the given reaction, which is first order with respect to both A and B: Rate $r = K[A]^1[B]^1$ $$0.1 = K(20)^1(0.5)^1 \cdots (i)$$ $$0.40 = K(x)^1(0.5)^1 \cdots (ii)$$ $$0.80 = K(40)^1(y)^1 \cdots (iii)$$ From (i) and (ii) $$x = 80$$ From (i) and (iii) $$y = 2$$
Question 66
Chemistry · Structure of Atom · Single correct
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R : Assertion A: In the photoelectric effect, the electrons are ejected from the metal surface as soon as the beam of light of frequency greater than threshold frequency strikes the surface. Reason R : When the photon of any energy strikes an electron in the atom, transfer of energy from the photon to the electron takes place. In the light of the above statements, choose the most appropriate answer from the options given below :
Both A and R are correct and R is the correct explanation of A
A is correct but R is not correct
Both A and R are correct but R is NOT the correct explanation of A
A is not correct but R is correct
Answer: (b)
Solution
The threshold frequency is the minimum frequency required for emission of electrons from the outermost shell. The light with frequencies lower than threshold would not eject photoelectrons from the shell of an atom. As for the emission kinetic energy of an electron should be greater than or equal to zero. Hence, the photoelectric emission will take place only when the energy of a photon is greater than the energy possessed by the electron. Atoms are ionised resulting in transfer of energy when photons of sufficient energy strike the metal surface.
Question 67
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: A solution of the product obtained by heating a mole of glycine with a mole of chlorine in presence of red phosphorous generates chiral carbon atom. Reason R: A molecule with 2 chiral carbons is always optically active. In the light of above statements, chose the correct answer from the options given below:
A is true but R is false
Both A and R are true but R is the correct explanation of A
A is false but R is true
Both A and R are true but R is NOT the correct explaination of A
Answer: (a)
Solution
When glycine is treated with chlorine in presence of red phosphorus, HVZ reaction takes place i.e., substitution of chlorine takes place at alpha carbon. $$\mathrm{H_2N - CH_2 - COOH \xrightarrow{Red P \atop Cl_2} H_2N - \overset{*}{CH} - COOH \atop (HVZ)}$$ Optically active A molecule with two chiral carbons is not always optically active. Suppose the following compound is having two chiral carbons but optically inactive due to internal compensation of optical rotation.
Question 68
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
Product [X] formed in the above reaction is:
Answer: (c)
Solution
The alcohol is reacted with a mixture of sodium iodide and concentrated phosphoric acid, $\mathrm{H_3PO_4}$, and the iodoalkane is distilled off. The 2-iodobutane formed in the previous reaction gives Grignard reagent with magnesium metal in dry ether. The Grignard reagent formed reacts with $\mathrm{D_2O}$ to give 2-deuterobutane.
Question 69
Chemistry · Polymers · Single correct
Given below are two statements: Statement I: Ethane at 333 to 343 K and 6 - 7 atm pressure in the presence of $AlEt_3$ and $TiCl_4$ undergoes addition polymerization to give LDP. Statement II: Caprolactam at 533 - 543 K in $H_2O$ through step growth polymerizes to give Nylon 6. In the light of the above statements, choose the correct answer from the options given below:
Statement I is false but Statement II is true
Statement I is true but Statement II is false
Both Statement I and Statement II are true
Both Statement I and Statement II are false
Answer: (a)
Solution
Low Density Polyethylene is obtained by the polymerisation of ethene under high pressure of $1000 - 2000 \, \mathrm{atm}$ at $350 - 570 \, \mathrm{K}$ in the presence of an initiator. High Density Polyethylene is obtained when polymerisation is done in the presence of Ziegler-Natta catalyst at $333 - 343 \, \mathrm{K}$ under $6 - 7 \, \mathrm{atm}$ pressure. Nylon-6 is manufactured from the monomer called caprolactam. The monomer caprolactam is heated at $533 - 543 \, \mathrm{K}$ in an inert atmosphere, it polymerises to give nylon-6.
Question 70
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Compound 'B' is
Answer: (a)
Solution
Nitrous acid gives nitrosonium ion as electrophile ($\mathrm{NO^+}$) which attacks phenol at less hindered p-position of form p-nitrosophenol. The nitroso group undergoes reduction and forms amine in the presence of $\mathrm{NH_4SH}$.
Question 71
Chemistry · The Solid State · Single correct
Which one of the following pairs is an example of polar molecular solids?
$\mathrm{SO_2(s)}, \mathrm{CO_2(s)}$
$\mathrm{SO_2(s)}, \mathrm{NH_3(s)}$
$\mathrm{MgO(s)}, \mathrm{SO_2(s)}$
$\mathrm{HCl(s)}, \mathrm{AlN(s)}$
Answer: (b)
Solution
SO$_2$ is a bent molecule with a central sulfur atom bonded to two oxygen atoms. The oxygen atoms are more electronegative than sulfur, causing a separation of charge. This results in a bent molecular geometry and a net dipole moment, making SO$_2$ a polar molecule. NH$_3$ is a trigonal pyramidal molecule with a central nitrogen atom bonded to three hydrogen atoms. Again, the electronegativity difference between nitrogen and hydrogen leads to a separation of charge. The arrangement of the atoms in NH$_3$ gives it a net dipole moment, making it a polar molecule.
Question 72
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct
One mole of $P_4$ reacts with 8 moles of $SOCl_2$ to give 4 moles of A, $x$ mole of $SO_2$ and 2 moles of B. A, B and $x$ respectively are
$POCl_3$, $S_2Cl_2$ and 2
$PCl_3$, $S_2Cl_2$ and 4
$PCl_3$, $S_2Cl_2$ and 2
$POCl_3$, $S_2Cl_2$ and 4
Answer: (b)
Solution
Thionyl chloride reacts with white phosphorus to produce phosphorus trichloride. The other side products in this reaction are sulphur dioxide and sulphur monochloride. $$\mathrm{P_4 + 8SOCl_2 \rightarrow 4PCl_3 + 4SO_2 + 2S_2Cl_2}$$ Hence $A = \mathrm{PCl_3}$, $x = 4$, $B = \mathrm{S_2Cl_2}$.
Question 73
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Compound from the following that will not produce precipitate on reaction with $\mathrm{AgNO_3}$ is
Answer: (d)
Solution
Compounds which result in the formation of stable carbocation upon treating with $\mathrm{AgNO_3}$ will produce precipitate. $$Br \xrightarrow{\mathrm{AgNO_3}} Aromatic$$ $$Br \xrightarrow{\mathrm{AgNO_3}} Unstable$$ $$Br \xrightarrow{\mathrm{AgNO_3}} Benzylic$$ $$CH = CH - Br \xrightarrow{\mathrm{AgNO_3}} Allylic$$ In the above carbocations, the second carbocation is unstable, hence, it cannot give precipitate with silver nitrate.
Question 74
Chemistry · Some Basic Concepts of Chemistry · Single correct
A solution is prepared by adding 2 g of ''X'' to 1 mole of water. Mass percent of ''X'' in solution is
5$\%$
20$\%$
2$\%$
10$\%$
Answer: (d)
Solution
To calculate the mass percent of "X" in the solution, we need to determine the mass of "X" and the total mass of the solution. Given: Solute (X) = 2 $\mathrm{g}$ Solvent ($\mathrm{H_2O}$) = 1 mole = 18 $\mathrm{g}$ Total mass = 2 + 18 = 20 $\mathrm{g}$ Mass percent of X = $\frac{2}{2+18}$ $\times$ 100 = 10
Question 75
Chemistry · General Principles and Processes of Isolation of Elements · Single correct
Given below are two statements: Statement I: In the metallurgy process, sulphide ore is converted to oxide before reduction. Statement II: Oxide ores in general are easier to reduce. In the light of the above statements, choose the most appropriate answer from the options given below:
Statement I is correct but Statement II is incorrect
Both Statement I and Statement II are incorrect
Statement I is incorrect but Statement II is correct
Both Statement I and Statement II are correct
Answer: (d)
Solution
Both Statement I and Statement II are correct. In many metallurgical processes, sulphide ores are first converted to oxide ores through a process known as roasting or calcination. The conversion of sulphide ore to oxide ore is done to remove the sulphur and simplify the subsequent reduction process. Oxide ores are generally easier to reduce compared to sulphide ores. This is because oxygen is already bonded to the metal in oxide ores, making it easier to remove the oxygen and extract the metal through reduction reactions.
Question 76
Chemistry · The s-Block Elements · Single correct
Alkali metal from the following with least melting point is
Cs
Rb
Na
K
Answer: (a)
Solution
On moving down the group in alkali metals, the melting point generally decreases. As you move down the alkali metal group (Group 1 of the periodic table), the atomic size or atomic radius increases. This increase in atomic size leads to a decrease in the strength of metallic bonds between the alkali metal atoms. Weaker metallic bonding results in lower melting points because less energy is required to overcome these weaker bonds and convert the solid metal into a liquid state. On moving down the group in alkali metals, the melting point generally decreases. As you move down the alkali metal group (Group 1 of the periodic table), the atomic size or atomic radius increases. This increase in atomic size leads to a decrease in the strength of metallic bonds between the alkali metal atoms. Weaker metallic bonding results in lower melting points because less energy is required to overcome these weaker bonds and convert the solid metal into a liquid state. \[ \begin{array}{c|c} \text{Element} & \text{M.P. (K)} \\ \hline \mathrm{Na} & 371 \\ \mathrm{K} & 336 \\ \mathrm{Rb} & 312 \\ \mathrm{Cs} & 302 \end{array} \]
Question 77
Chemistry · Solutions · Single correct
What weight of glucose must be dissolved in $100\,\mathrm{g}$ of water to lower the vapour pressure by $0.20\,\mathrm{mm\,Hg}$? (Assume a dilute solution is being formed.) Given: Vapour pressure of pure water is $54.2\,\mathrm{mm\,Hg}$ at room temperature. Molar mass of glucose is $180\,\mathrm{g\,mol^{-1}}$.
3.59 g
3.69 g
4.69 g
2.59 g
Answer: (b)
Solution
Sol. Using the formula $$\frac{P^o - P_s}{P^o} = \frac{Moles of solute}{Moles of solvent}$$ (for dilute solution) where $P^o$ is the vapour pressure of pure water and $P_s$ is the vapour pressure of the solution. $$\frac{54.2 - 54}{54.2} = \frac{w/180}{100/18}$$ $$w = \frac{0.2 \times 1000}{54.2}$$ $$= \frac{200}{54.2} = 3.69$$
Question 78
Chemistry · Co-ordination Compounds · Single correct
The magnetic moment is measured in Bohr Magneton (BM). Spin only magnetic moment of Fe in $[\mathrm{Fe} (\mathrm{H}_2\mathrm{O})_6]^{3+}$ and $[\mathrm{Fe} (\mathrm{CN})_6]^{3-}$ complexes respectively is:
6.92 B. M. in both
3.87 B. M. and 1.732 B. M.
5.92 B. M. and 1.732 B. M.
4.89 B. M. and 6.92 B. M.
Answer: (c)
Solution
The spin only magnetic moment can be calculated as follows $$\mu = \sqrt{n(n+2)} BM$$ $n =$ Number of unpaired electrons $$[Fe (H_2O)_6]^{3+} = d^5 (High spin complex) = 5 unpaired electrons$$ $$\mu = \sqrt{5 \times 7} = \sqrt{35}$$ $$= 5.92 B.M.$$ $$[Fe (CN)_6]^{3+} = d^5 (Low spin complex) = 1$$ $$\mu = \sqrt{1 \times 3} = \sqrt{3}$$ $$= 1.732 B.M.$$
Question 79
Chemistry · Co-ordination Compounds · Single correct
Match List I with List II Choose the correct answer from the options given below:
A-III, B-IV, C-II, D-I
A-II, B-III, C-I, D-IV
A-II, B-IV, C-I, D-III
A-II, B-III, C-IV, D-I
Answer: (b)
Solution
The formula $\mathrm{Mg(NH_4)PO_4}$ represents magnesium ammonium phosphate; it is white in colour. $\mathrm{K_3[Co(NO_2)_6]}$ is known as potassium hexanitritocobaltate(III). It is yellow in colour. The yellow colour is due to the presence of the cobalt ion ($\mathrm{Co^{3+}}$) in the complex, which absorbs certain wavelengths of light and reflects yellow light. $\mathrm{MnO(OH)_2}$ is brown in colour. $\mathrm{Fe_4[Fe(CN)_6]_3}$ is blue in colour.
Question 80
Chemistry · Co-ordination Compounds · Single correct
If $\mathrm{Ni}^{2+}$ is replaced by $\mathrm{Pt}^{2+}$ in the complex $[\mathrm{NiCl}_2 \mathrm{Br}_2]^{2-}$, which of the following properties are expected to get changed?
A and D
A, B and C
B and C
A, B and D
Answer: (d)
Solution
When $\mathrm{Ni^{2+}}$ is replaced by $\mathrm{Pt^{2+}}$ in the complex $[\mathrm{NiCl_2 \, Br_2}]^{2-}$, the following properties are expected to be changed: A. Geometry: Since $\mathrm{Pt^{2+}}$ and $\mathrm{Ni^{2+}}$ have different coordination preferences and atomic sizes, the replacement is likely to result in a change in the geometry of the complex. That is it changes to square planar. B. Geometrical isomerism: If the replacement of $\mathrm{Ni^{2+}}$ with $\mathrm{Pt^{2+}}$ leads to a change in the ligand arrangement, it can result in the generation of cis and trans isomers. C. Magnetic properties: $[\mathrm{PtCl_2 \, Br_2}]^{2-}$ is diamagnetic. Both the complex species are optically inactive.
Question 81
Chemistry · Biomolecules · Numerical
Number of compounds from the following which will not produce orange red precipitate with Benedict solution is....... Glucose, maltose, sucrose, ribose, 2-deoxyribose, amylose, lactose
Answer: 2
Solution
Except sucrose and amylose all others, give orange red precipitate with Benedict solution. Sucrose is a non-reducing disaccharide composed of glucose and fructose. It does not have a free aldehyde or ketone group and, therefore, cannot undergo oxidation and reduce the Benedict's reagent. As a result, sucrose will not produce an orange-red precipitate with the Benedict's solution. Amylose is a polysaccharide composed of multiple glucose units linked together. While glucose, a monosaccharide, is a reducing sugar, the glycosidic bonds in amylose prevent the free aldehyde or ketone group from being available for oxidation. As a result, amylose, as a part of starch, does not give a positive Benedict's test and will not produce an orange-red precipitate.
Question 82
Chemistry · Equilibrium · Numerical
4.5 moles each of hydrogen and iodine is heated in a sealed ten litre vessel. At equilibrium, 3 moles of HI were found. The equilibrium constant for $$\mathrm{H_2(g) + I_2(g) \rightleftharpoons 2HI_{(g)}}$$ is ........
Answer: 1
Solution
The equilibrium moles of each reactant and product can be calculated as follows, $$\mathrm{H_2(g) + I_2(g) \rightleftharpoons 2HI(g)}$$ Initial: $$\begin{array}{ccc} 4.5 & 4.5 & 0 \\ \end{array}$$ At equilibrium: $$\begin{array}{ccc} 4.5 - 1.5 & 4.5 - 1.5 & 3 \\ \end{array}$$ Now, using equilibrium moles, equilibrium constant calculated as shown below. $$K_{eq} = \frac{[\mathrm{HI}]^2}{[\mathrm{H_2}] [\mathrm{I_2}]} = \frac{(3)^2}{3 \times 3} = 1$$
Question 83
Chemistry · Surface Chemistry · Numerical
The number of correct statements about modern adsorption theory of heterogeneous catalysis from the following is ...... A. The catalyst is diffused over the surface of reactants. B. Reactants are adsorbed on the surface of the catalyst. C. Occurrence of chemical reaction on the catalyst’s surface through formation of an intermediate. D. It is a combination of intermediate compound formation theory and the old adsorption theory. E. It explains the action of the catalyst as well as those of catalytic promoters and poisons.
The catalyst is diffused over the surface of reactants.
Reactants are adsorbed on the surface of the catalyst.
Occurrence of chemical reaction on the catalyst's surface through formation of an intermediate.
It is a combination of intermediate compound formation theory and the old adsorption theory.
Answer: (c)
Solution
Adsorption theory of Heterogeneous catalysis involves five steps- 1. Diffusion of reactants to the surface of the catalyst. 2. Adsorption of reactant molecules on the surface of the catalyst. (Occurrence of chemical reaction on the catalyst's surface through formation of an intermediate.) 3. Desorption of reaction products from the catalyst surface. 4. Making the surface available again for more reaction to occur. 5. Diffusion of reaction products away from the catalyst's surface. So, we can deduce from Adsorption theory of catalysis that as the concentration of reactants at active centres increases due to adsorption and thus the rate of the reaction is also increased.
Question 84
Chemistry · Structure of Atom · Numerical
The number of correct statements from the following is .......... A. For $1\text{s}$ orbital, the probability density is maximum at the nucleus. B. For $2\text{s}$ orbital, the probability density first increases to maximum and then decreases sharply to zero. C. Boundary surface diagrams of the orbitals encloses a region of $100\%$ probability of finding the electron. D. $\text{p}$ and $\text{d}$-orbitals have $1$ and $2$ angular nodes respectively. E. Probability density of $\text{p}$-orbital is zero at the nucleus.
For 1s orbital, the probability density is maximum at the nucleus
For 2s orbital, the probability density first increases to maximum and then decreases sharply to zero.
Boundary surface diagrams of the orbitals encloses a region of 100$\%$ probability of finding the electron.
p and d-orbitals have 1 and 2 angular nodes respectively
Answer: (c)
Solution
Probability density curves for 1s, 2s, and 2p orbitals are given below. For 1s orbital, the probability density is maximum at the nucleus. For 2s orbital, the probability density first decreases and then increases. At any distance from the nucleus, the probability density of finding an electron is never zero, and it always has some finite value. The number of angular nodes is equal to the azimuthal quantum number. For p-orbital, it is equal to 1, and for d-orbital, it is equal to 2. Probability density of p-orbital is zero at the nucleus.
The number of possible isomeric products formed when 3-chloro-1-butene reacts with HCl through carbocation formation is........
Answer: 4
Solution
3-chloro-1-butene undergo protonation and gives secondary carbocation according Markonikov's addition in the first step. In the second step the lone pair on the chlorine attacks the positively charged carbon to form cyclic intermediate. Now the nucleophile in the reaction i.e., chloride ion attacks cyclic intermediate and forms two structural products as shown below. 2,2-dichlorobutane exit in single isomer only, but 2,3-dichlorobutane exhibits three isomers.
Question 86
Chemistry · The s-Block Elements · Fill in the blank
$\mathrm{Mg(NO_3)_2}\cdot X\mathrm{H_2O}$ and $\mathrm{Ba(NO_3)_2}\cdot Y\mathrm{H_2O}$ represent the formulae of the crystalline forms of nitrate salts. Sum of $X$ and $Y$ is _______.
Answer: 6
Solution
Magnesium nitrate crystallises with six molecules of water, whereas barium nitrate is anhydrous salts. The hydrated form of magnesium nitrate is $\mathrm{Mg(NO_3)_2} \cdot 6\mathrm{H_2O}$ and anhydrous salt of barium nitrate is $\mathrm{Ba(NO_3)_2}$ respectively. Therefore, $x = 6$, $y = 0$.
Question 87
Chemistry · Some Basic Concepts of Chemistry · Fill in the blank
The total number of intensive properties from the following is.......... Volume, Molar heat capacity, molarity, $E^0_{cell}$, Gibbs free energy change, Molar mass, Mole
Answer: 4
Solution
An intensive property is a physical quantity whose value does not depend on the amount of substance which was measured. Molar heat capacity, molarity, $E^0_{cell}$ and molar mass are intensive properties. An extensive property of a system depends on the system size or the amount of matter in the system. Volume, Gibbs free energy change, Mole are extensive properties.
Question 88
Chemistry · Chemical Bonding and Molecular Structure · Fill in the blank
The maximum number of lone pairs of electron on the central atom from the following species is ...... $\mathrm{ClO_3^-},\quad XeF_4,\quad SF_4,\quad \text{and}\quad \mathrm{I_3^-}$
Answer: 3
Solution
$\mathrm{ClO_3^-}$: The central atom is Cl. There is one lone pair of electrons on the central atom. $\mathrm{XeF_4}$: The central atom is Xe. It has two lone pairs on the central atom. $\mathrm{SF_4}$: The central atom is S. It contains one lone pair on the central atom. $\mathrm{I_3^-}$: The central atom is I. It contains three lone pairs on the central atom.
Question 89
Chemistry · Some Basic Concepts of Chemistry · Numerical
The volume of hydrogen liberated at STP by treating $2.4 \, \mathrm{g}$ of magnesium with excess of hydrochloric acid is _______ $\times 10^{-2} \, \mathrm{L}$. Given Molar volume of gas is $22.4 \, \mathrm{L}$ at STP. Molar mass of magnesium is $24 \, \mathrm{g} \, \mathrm{mol}^{-1}$
Answer: 224
Solution
The stoichiometric equation of the reaction between magnesium and hydrogen chloride can be written as follows. One mole magnesium can liberate one mole of hydrogen gas according to the following equation. $$\mathrm{Mg} + 2\mathrm{HCl} \rightarrow \mathrm{MgCl_2} + \mathrm{H_2}$$ $$2.4 \, \mathrm{g} = 0.1 \, mole 0.1 \, mole$$ Volume of 1 mole $\mathrm{H_2}$ at STP = 22.4 L Therefore, 0.1 mole $\mathrm{H_2}$ at STP will occupy = 2.24 L
Question 90
Chemistry · Electrochemistry · Numerical
The number of correct statements from the following is.......... A. $E_{\mathrm{cell}}$ is an intensive parameter. B. A negative $E^\circ$ means that the redox couple is a stronger reducing agent than the $\mathrm{H^+/H_2}$ couple. C. The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction. D. The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte.
E_{cell} is an intensive parameter
A negative E^0 means that the redox couple is a stronger reducing agent than the H^+/H_2 couple.
The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction.
The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte.
Answer: (d)
Solution
An intensive property is a bulk property, meaning that it is a physical property of a system that does not depend on the system size or the amount of material in the system. $$\Delta G = -nF E_{cell}$$ The $$\Delta G$$ in the above equation is an extensive property, $$E_{cell}$$ is an intensive property. A negative $$E^0$$ means that the redox couple is a stronger reducing agent than the $$\mathrm{H^+/H_2}$$ couple. The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction. The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte.