JEE Main 28 January 2025 Shift 2 question paper with solutions
JEE Main 28 January 2025 Shift 2: all 75 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 · Probability · Single correct
Bag $B_1$ contains 6 white and 4 blue balls, Bag $B_2$ contains 4 white and 6 blue balls, and Bag $B_3$ contains 5 white and 5 blue balls. One of the bags is selected at random and a ball is drawn from it. If the ball is white, then the probability, that the ball is drawn from Bag $B_2$, is:
$\frac{4}{15}$
$\frac{1}{3}$
$\frac{2}{5}$
$\frac{2}{3}$
Answer: (a)
Solution
Given: $E_1$: Bag $B_1$ is selected $B_1$: 6W4B, $B_2$: 4W6B, $B_3$: 5W5B $E_2$: Bag $B_2$ is selected $E_3$: Bag $B_3$ is selected $A$: Drawn ball is white We have to find $P \left( \frac{E_2}{A} \right)$ $$P \left( \frac{E_2}{A} \right) = \frac{P(E_2)P \left( \frac{A}{E_2} \right)}{P(E_1)P \left( \frac{A}{E_1} \right) + P(E_2)P \left( \frac{A}{E_2} \right) + P(E_3)P \left( \frac{A}{E_3} \right)}$$ $$= \frac{\frac{1}{3} \times \frac{4}{10}}{\frac{1}{3} \times \frac{6}{10} + \frac{1}{3} \times \frac{4}{10} + \frac{1}{3} \times \frac{5}{10}}$$ $$= \frac{4}{15}$$
Question 2
Maths · Vector Algebra · Single correct
Let A, B, C be three points in $xy$-plane, whose position vector are given by $\sqrt{3} \hat{i} + \hat{j}$, $\hat{i} + \sqrt{3} \hat{j}$ and $a \hat{i} + (1-a) \hat{j}$ respectively with respect to the origin O. If the distance of the point C from the line bisecting the angle between the vectors $\overrightarrow{OA}$ and $\overrightarrow{OB}$ is $\frac{9}{\sqrt{2}}$, then the sum of all the possible values of $a$ is:
2
9/2
1
0
Answer: (c)
Solution
Equation of line in the internal bisector of $OA$ and $OB$ is $(\sqrt{3} + 1)\hat{i} + (\sqrt{3} + 1)\hat{j}$. Therefore, the line will be $y = x \Rightarrow x - y = 0$. $$D = \left| \frac{a - (1-a)}{\sqrt{a^2 + (1-a)^2}} \right| = \frac{9}{\sqrt{2}}$$ $$(2a - 1)^2 = \frac{81}{2} \left( a^2 + (1-a)^2 \right)$$ $$\Rightarrow 2 \left( 4a^2 - 4a + 1 \right) = 81a^2 + 8a^2 - 162a - 81$$ $$\Rightarrow 162a^2 - 162a + 81 - 8a^2 + 8a - 2 = 0$$ $$\Rightarrow 154a^2 - 154a + 79 = 0$$ Sum of values $= -\frac{-154}{154} = 1$
Question 3
Maths · Vector Algebra · Single correct
If the components of $\vec{a} = \alpha \hat{i} + \beta \hat{j} + \gamma \hat{k}$ along and perpendicular to $\vec{b} = 3\hat{i} + \hat{j} - \hat{k}$ respectively, are $\frac{16}{11} (3\hat{i} + \hat{j} - \hat{k})$ and $\frac{1}{11} (-4\hat{i} - 5\hat{j} - 17\hat{k})$, then $\alpha^2 + \beta^2 + \gamma^2$ is equal to :
Maths · Complex Numbers and Quadratic Equations · Single correct
If $\alpha + i \beta$ and $\gamma + i \delta$ are the roots of $x^2 - (3 - 2i)x - (2i - 2) = 0$, $i = \sqrt{-1}$, then $\alpha \gamma + \beta \delta$ is equal to:
$-2$
$6$
$-6$
$2$
Answer: (d)
Solution
Given the equation $x^2 - (3 - 2i)x - (2i - 2) = 0$. Using the quadratic formula, we have: $$x = \frac{(3 - 2i) \pm \sqrt{(3 - 2i)^2 - 4(1)(-(2i - 2))}}{2(1)}$$ Simplifying inside the square root: $$(3 - 2i) \pm \sqrt{9 - 4 - 12i + 8}$$ This becomes: $$\frac{3 - 2i \pm \sqrt{-3 - 4i}}{2}$$ Further simplifying: $$3 - 2i \pm \sqrt{(1)^2 + (2i)^2 - 2(1)(2i)}$$ This simplifies to: $$\frac{3 - 2i \pm (1 - 2i)}{2}$$ Thus, we have two solutions: $$\frac{3 - 2i + 1 - 2i}{2} or \frac{3 - 2i - 1 + 2i}{2}$$ This results in: $$2 - 2i or 1 + 0i$$ So $\alpha \gamma + \beta \delta = 2(1) + (-2)(0) = 2$$
Question 5
Maths · Conic Sections · Single correct
If the midpoint of a chord of the ellipse $\frac{x^2}{9} + \frac{y^2}{4} = 1$ is $(\sqrt{2}, 4/3)$, and the length of the chord is $\frac{2\sqrt{\alpha}}{3}$, then $\alpha$ is :
20
22
18
26
Answer: (b)
Solution
Given the ellipse equation $E: \frac{x^2}{9} + \frac{y^2}{4} = 1$ and the tangent $T = S_1$. $$\Rightarrow \frac{\sqrt{2x}}{9} + \frac{1}{3} \left(4 \left(\frac{4}{3} y\right) - 1 \right) = \frac{2}{9} + \frac{16}{9(4)} - 1$$ $$\frac{\sqrt{2x}}{9} + \frac{y}{3} = \frac{2}{9} + \frac{4}{9}$$ $$\frac{\sqrt{2x}}{9} + \frac{y}{3} = \frac{2}{3} \Rightarrow \sqrt{2x} + 3y = 6$$ Now the point of intersection of the chord and ellipse is $$\frac{(6 - 3y)^2}{18} + \frac{y^2}{4} = 1$$ $$(2 - y)^2 + \frac{y^2}{2} = 1$$ $$2 \left(4 + y^2 - 4y\right) + y^2 = 4$$ $$\Rightarrow 3y^2 - 8y + 4 = 0$$ $$\Rightarrow y = 2, \frac{2}{3}$$ So, points are $(0, 2)$ are $\left(2\sqrt{2}, \frac{2}{3}\right)$. Length of chord $= \sqrt{(2\sqrt{2})^2 + \left(\frac{2}{3} - 2\right)^2}$ $$= \sqrt{8 + \frac{16}{9}}$$ $$= \frac{\sqrt{88}}{3} = \frac{2\sqrt{22}}{3}$$ On comparing $\alpha = 22$
Question 6
Maths · Probability · Single correct
Let S be the set of all the words that can be formed by arranging all the letters of the word GARDEN. From the set S, one word is selected at random. The probability that the selected word will NOT have vowels in alphabetical order is:
$\frac{1}{2}$
$\frac{1}{4}$
$\frac{2}{3}$
$\frac{1}{3}$
Answer: (a)
Solution
Probability (P) = $\frac{favourable case}{Total case}$ (when A $\&$ E are in order) Total case = 6! Favourable case = $\binom{6}{2}$ $\cdot$ 4! $$P = \frac{(15)4!}{(30)4!}$$ Probability when not in order = 1 - $\frac{1}{2}$ = $\frac{1}{2}$
Question 7
Maths · Integrals · Single correct
Let $f$ be a real valued continuous function defined on the positive real axis such that $g(x)=\int_{0}^{x} t\,f(t)\,dt$. If $g(x^3)=x^6+x^7$, then value of $\sum_{r=1}^{15} f(r^3)$ is ______.
270
340
320
310
Answer: (d)
Solution
Given $g(x) = x^2 + x^{7/3}$. The derivative is $g'(x) = 2x + \frac{7}{3} x^{4/3}$. Let $f(x) = \frac{g'(x)}{x}$. Then $f(x) = 2 + \frac{7}{3} x^{1/3}$. For $f(r^3)$, we have $f(r^3) = 2 + \frac{7}{3} r$. The sum is $$\sum_{r=1}^{15} \left( 2 + \frac{7}{3} r \right) = 2(15) + \frac{7}{3} \left( \frac{15(16)}{2} \right) = 310.$$
Question 8
Maths · Three Dimensional Geometry · Single correct
The square of the distance of the point $\left( \frac{15}{7}, \frac{32}{7}, 7 \right)$ from the line $\frac{x+1}{3} = \frac{y+3}{5} = \frac{z+5}{7}$ in the direction of the vector $\hat{i} + 4\hat{j} + 7\hat{k}$ is:
54
44
41
66
Answer: (d)
Solution
Line L is given by $\($ $\frac{x+1}{3}$ = $\frac{y+3}{5}$ = $\frac{z+5}{7}$ $\)$. The line PQ is given by $\($ $\frac{x - \frac{15}{7}}{1}$ = $\frac{y - \frac{32}{7}}{4}$ = $\frac{z - 7}{7}$ = $\lambda$ $\)$. Therefore, point Q is $\($ $\left$( $\lambda$ + $\frac{15}{7}$, 4$\lambda$ + $\frac{32}{7}$, 7$\lambda$ + 7 $\right$) $\)$. Since Q lies on line L, we have $\($ $\frac{\lambda + \frac{15}{7} + 1}{3}$ = $\frac{7\lambda + 7 + 5}{7}$ $\)$. This simplifies to $\($ 7$\lambda$ + 22 = 21$\lambda$ + 36 $\)$, giving $\($ $\lambda$ = -1 $\)$. Thus, point Q is $\($ $\left$( $\frac{8}{7}$, $\frac{4}{7}$, 0 $\right$) $\)$. The distance PQ is $\($ $\sqrt{ \left( \frac{15}{7} - \frac{8}{7} \right)^2 + \left( \frac{32}{7} - \frac{4}{7} \right)^2 + (7 - 0)^2 }$ $\)$. Therefore, $\($ PQ = $\sqrt{66}$ $\)$ and $\($ (PQ)^2 = 66 $\)$.
Question 9
Maths · Applications of Integrals · Single correct
The area of the region bounded by the curves $x$ $(1 + y^2)$ = $1$ and $y^2 = 2x$ is:
2 ( $\frac{\pi}{2}$ - $\frac{1}{3}$)
$\frac{\pi}{2}$ - $\frac{1}{3}$
$\frac{\pi}{4}$ - $\frac{1}{3}$
$\frac{1}{2}$ ( $\frac{\pi}{2}$ - $\frac{1}{3}$)
Answer: (b)
Solution
Given the equations $x(1 + y^2) = 1$ and $y^2 = 2x$. From equation (1) and (2), $x(1 + 2x) = 1 \Rightarrow 2x^2 + x - 1 = 0$. Solving for $x$, we get $x = \frac{1}{2}$ and $x = -1$ (Reject). Therefore, $y^2 = 2 \left( \frac{1}{2} \right)$ which implies $y = \pm 1$. The area bounded is given by $$\int_{-1}^{1} \left( \frac{1}{1 + y^2} - \frac{y^2}{2} \right) \, dy$$ which evaluates to $$\left( \tan^{-1} y - \frac{y^3}{6} \right) \bigg|_{-1}^{1}$$ resulting in $$\frac{\pi}{2} - \frac{1}{3}.$$
Question 10
Maths · Matrices · Single correct
Let $A = \begin{bmatrix} \frac{1}{\sqrt{2}} & -2 \\ 0 & 1 \end{bmatrix}$ and $P = \begin{bmatrix} \cos \theta & -\sin \theta \\ \sin \theta & \cos \theta \end{bmatrix}$, $\theta > 0$. If $B = PAP^T$, $C = P^TB^{10}P$ and the sum of the diagonal elements of $C$ is $\frac{m}{n}$, where $\gcd(m, n) = 1$, then $m + n$ is:
127
258
65
2049
Answer: (c)
Solution
Given $\($ P = $\begin{bmatrix}$ $\cos$ $\theta$ & -$\sin$ $\theta$ $\\$ $\sin$ $\theta$ & $\cos$ $\theta$ $\end{bmatrix}$ $\)$. Therefore, $\($ P^T P = I $\)$. Let $\($ B = P A P^T $\)$. Pre-multiply by $\($ P^T $\)$ (Given): $\($ P^T B = P^T P A P^T = A P^T $\)$. Now post-multiply by $\($ P $\)$: $\($ P^T B P = A P^T P = A $\)$. So $\($ A^2 = P^T B P $\underline{P^T B P}$_{I} $\)$. $\($ A^2 = P^T B^2 P $\)$. Similarly, $\($ A^{10} = P^T B^{10} P = C $\)$. Given $\($ A = $\begin{bmatrix}$ $\frac{1}{\sqrt{2}}$ & -2 $\\$ 0 & 1 $\end{bmatrix}$ $\)$. $\($ $\Rightarrow$ A^2 = $\begin{bmatrix}$ $\frac{1}{2}$ & -$\sqrt{2}$ - 2 $\\$ 0 & 1 $\end{bmatrix}$ $\)$. Similarly check $\($ A^3 $\)$ and so on since $\($ C = A^{10} $\Rightarrow$ $\)$ Sum of diagonal elements of $\($ C $\)$ is $\($ $\left$( $\frac{1}{\sqrt{2}}$ $\right$)^{10} + 1 $\)$. $\($ = $\frac{1}{32}$ + 1 = $\frac{33}{32}$ = $\frac{m}{n}$ $\)$. $\($ $\gcd$(m, n) = 1 $\)$ (Given). $\($ $\Rightarrow$ m + n = 65 $\)$.
Question 11
Maths · Integrals · Single correct
If $f(x) = \int \dfrac{1}{x^{1/4}(1+x^{1/4})}\,dx$, $f(0) = -6$, then $f(1)$ is equal to :
Let $f : \mathbb{R} \to \mathbb{R}$ be a twice differentiable function such that $f(2) = 1$. If $F(x) = x f(x)$ for all $x \in \mathbb{R}$, $\int_0^2 x F'(x) \, dx = 6$ and $\int_0^2 x^2 F''(x) \, dx = 40$, then $F'(2) + \int_0^2 F(x) \, dx$ is equal to:
Maths · Relations and Functions (Advanced) · Single correct
Let $f : [0, 3] \to A$ be defined by $f(x) = 2x^3 - 15x^2 + 36x + 7$ and $g : [0, \infty) \to B$ be defined by $g(x) = \frac{x^{2025}}{x^{2025} + 1}$. If both the functions are onto and $S = \{ x \in \mathbb{Z} : x \in A \text{ or } x \in B \}$, then $n(S)$ is equal to:
29
30
31
36
Answer: (b)
Solution
As $f(x)$ is onto, hence $A$ is the range of $f(x)$. $$f'(x) = 6x^2 - 30x + 36$$ $$= 6(x - 2)(x - 3)$$ Now $$f(2) = 16 - 60 + 72 + 7 = 35$$ $$f(3) = 54 - 135 + 108 + 7 = 34$$ $$f(0) = 7$$ Hence range $\in [7, 35] = A$. Also for range of $g(x)$ $$g(x) = 1 - \frac{1}{x^{2025} + 1} \in (0, 1) = B$$ $$s = \{0, 7, 8, \ldots, 35\}$$ hence $n(s) = 30$.
Question 15
Maths · Relations and Functions · Single correct
Let $[x]$ denote the greatest integer less than or equal to $x$. Then the domain of \[ f(x)=\sec^{-1}(2[x]+1) \] is:
$(-\infty,-1]\cup[0,\infty)$
$(-\infty,-1]\cup[1,\infty)$
$(-\infty,\infty)$
$(-\infty,\infty)\setminus\{0\}$
Answer: (c)
Solution
Given $f(x) = \sec^{-1}(2[x] + 1)$. $\Rightarrow 2[x] + 1 \geq 1$ or $2[x] + 1 \leq -1$ $\Rightarrow 2[x] \geq 0$ or $2[x] \leq -2$ $\Rightarrow [x] \geq 0$ or $[x] \leq -1$ $\Rightarrow x \geq 0$ or $x \leq 0$ Domain of $f(x)$ is $(-\infty, \infty)$
Question 16
Maths · Trigonometric Functions · Single correct
If $\displaystyle \sum_{r=1}^{13} \left\{ \frac{1}{ \sin\left(\frac{\pi}{4}+(r-1)\frac{\pi}{6}\right) \sin\left(\frac{\pi}{4}+r\frac{\pi}{6}\right) } \right\} = a\sqrt{3}+b,$ where $a,b\in\mathbb{Z}$, then $a^2+b^2$ is equal to:
10
4
2
8
Answer: (d)
Solution
Given the expression $$\frac{1}{\sin \frac{\pi}{6}} \sum_{r=1}^{13} \frac{\sin \left[ \left( \frac{\pi}{4} + r \frac{\pi}{6} \right) - \left( \frac{\pi}{4} \right) - (r-1) \frac{\pi}{6} \right]}{\sin \left( \frac{\pi}{4} + (r-1) \frac{\pi}{6} \right) \sin \left( \frac{\pi}{4} + r \frac{\pi}{6} \right)}$$ which simplifies to $$\frac{1}{\sin \frac{\pi}{6}} \sum_{r=1}^{13} \left( \cot \left( \frac{\pi}{4} + (r-1) \frac{\pi}{6} \right) - \cot \left( \frac{\pi}{4} + r \frac{\pi}{6} \right) \right).$$ This evaluates to $$= 2\sqrt{3} - 2 = a \sqrt{3} + b.$$ So $$a^2 + b^2 = 8.$$
Question 17
Maths · Straight Lines and Pair of Straight Lines · Single correct
Two equal sides of an isosceles triangle are along $-x + 2y = 4$ and $x + y = 4$. If $m$ is the slope of its third side, then the sum, of all possible distinct values of $m$, is :
-2$\sqrt{10}$
12
6
-6
Answer: (c)
Solution
Slope of the third side $=$ slope of the perpendicular bisector of given lines $h:\;\dfrac{-x+\frac{2}{\sqrt2}y-4}{\sqrt5} =\pm\dfrac{x+\frac{1}{\sqrt2}y-4}{\sqrt2}$ $h_1:\;\sqrt2(-x+2y-4)=\sqrt5(x+y-4)$ $h_2:\;\sqrt2(-x+2y-4)=-\sqrt5(x+y-4)$ $M_{L_1}=-\dfrac{\sqrt5+\sqrt2}{\sqrt5-2\sqrt2}$ $M_{L_2}=\dfrac{\sqrt5-\sqrt2}{\sqrt5+2\sqrt2}$ $M_{L_1}+M_{L_2} =-\dfrac{\sqrt5+\sqrt2}{\sqrt5-2\sqrt2} +\dfrac{\sqrt5-\sqrt2}{\sqrt5+2\sqrt2}$ $=-\dfrac{(\sqrt5+\sqrt2)(\sqrt5+2\sqrt2)+(\sqrt5-\sqrt2)(\sqrt5-2\sqrt2)}{-3}$ $=6$
Question 18
Maths · Binomial Theorem · Single correct
Let the coefficients of three consecutive terms $T_r$, $T_{r+1}$ and $T_{r+2}$ in the binomial expansion of $(a + b)^{12}$ be in a G.P. and let $p$ be the number of all possible values of $r$. Let $q$ be the sum of all rational terms in the binomial expansion of $\left(\sqrt[4]{3} + \sqrt[3]{4}\right)^{12}$. Then $p + q$ is equal to:
283
287
295
299
Answer: (a)
Solution
Coefficient of $T_r, T_{r+1}, T_{r+2} \rightarrow GP$ $$\Rightarrow \left(^{12}C_r\right)^2 = ^{12}C_{r-1} \cdot ^{12}C_{r+1}$$ $$\Rightarrow \left(^{12}C_r\right)^2 = ^{12}C_{r-1} \cdot ^{12}C_{r+1}$$ but no three consecutive binomial coefficient are in GP $$\Rightarrow P = 0$$ Now for $\left(3^{1/4} + 4^{1/3}\right)^{12}$, $T_{r+1} = ^{12}C_r (4)^{K/3} (3)^{\frac{12-K}{4}}$ for rational terms $K = 0, 12$ sum of rational terms $$= ^{12}C_0 4^0 \cdot 3^3 + ^{12}C_{12} \cdot 4^4 \cdot 3^0$$ $$= 27 + 256 = 283 = q$$ $$\therefore p + q = 283$$
Question 19
Maths · Conic Sections · Single correct
If A and B are the points of intersection of the circle $x^2 + y^2 - 8x = 0$ and the hyperbola $\frac{x^2}{9} - \frac{y^2}{4} = 1$ and a point P moves on the line $2x - 3y + 4 = 0$, then the centroid of $\triangle PAB$ lies on the line:
$x + 9y = 36$
$4x - 9y = 12$
$6x - 9y = 20$
$9x - 9y = 32$
Answer: (c)
Solution
By solving $\frac{x^2}{9} - \left( \frac{8x - x^2}{4} \right) = 1$ we have: $$4x^2 - 72x + 9x^2 = 36$$ $$\Rightarrow 13x^2 - 72x - 36 = 0$$ $$\Rightarrow 13x^2 - 78x + 6x - 36 = 0$$ $$\Rightarrow 13x(x - 6) + 6(x - 6) = 0$$ $$\Rightarrow x = 6 or -\frac{13}{6} (neglected)$$ $$\Rightarrow y^2 = 8(6) - (6)^2$$ $$\Rightarrow y = \pm \sqrt{12}$$ So, points $A$ and $B$ are $(6, \sqrt{12})$, $(6, -\sqrt{12})$. Point $P \left( h, \frac{2h+4}{3} \right)$. Centroid of $\triangle PAB$ is $\left( \frac{12+h}{3}, \frac{2h+4}{9} \right)$. By options, this centroid lies on the line $6x - 9y = 20$.
Question 20
Maths · Relations and Functions · Single correct
Let $f : \mathbb{R} - \{0\} \to (-\infty, 1)$ be a polynomial of degree 2, satisfying $f(x)f\left(\frac{1}{x}\right) = f(x) + f\left(\frac{1}{x}\right)$. If $f(K) = -2K$, then the sum of squares of all possible values of $K$ is :
7
6
1
9
Answer: (b)
Solution
As $f(x)$ is a polynomial of degree two, let it be $$f(x) = ax^2 + bx + c (a \neq 0)$$ On satisfying given conditions, we get $C = 1$ and $a = \pm 1$. Hence, $f(x) = 1 \pm x^2$. Also, range $\in (-\infty, 1]$, hence $$f(x) = 1 - x^2$$ Now $f(k) = -2k$. $$1 - k^2 = -2k \rightarrow k^2 - 2k - 1 = 0$$ Let roots of this equation be $\alpha$ and $\beta$, then $$\alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha\beta = 4 - 2(-1) = 6$$
Question 21
Maths · Permutations and Combinations · Numerical
The number of natural numbers, between 212 and 999, such that the sum of their digits is 15, is
Answer: 64
Solution
Let the number be $$2ab, \ a + b = 13$$ Thus, $a, b \in \{0, 9\}$ This gives 6 numbers $\{(9, 4), (8, 5), \ldots, (4, 9)\}$. Similarly, for $3ab, \ a + b = 12 \Rightarrow 7$ numbers. For $4ab, \ a + b = 11 \Rightarrow$ Numbers. For $5ab, \ a + b = 10 \Rightarrow 9$ numbers. For $6ab, \ a + b = 9 \Rightarrow 10$ numbers. For $7ab, \ a + b = 8 \Rightarrow 9$ numbers. For $8ab, \ a + b = 7 \Rightarrow 8$ numbers. For $9ab, \ a + b = 6 \Rightarrow 7$ numbers. Therefore, total ways $= 64$.
Question 22
Maths · Limits and Derivatives · Numerical
Let $f(x) = \lim_{n \to \infty} \sum_{r=0}^{n} \left( \frac{\tan(x/2^{r+1}) + \tan^3(x/2^{r+1})}{1 - \tan^2(x/2^{r+1})} \right)$. Then $\lim_{x \to 0} \frac{e^{x} - e^{f(x)}}{x - f(x)}$ is equal to
The interior angles of a polygon with $n$ sides, are in an A.P. with common difference $6^\circ$. If the largest interior angle of the polygon is $219^\circ$, then $n$ is equal to
Let A and B be the two points of intersection of the line $y + 5 = 0$ and the mirror image of the parabola $y^2 = 4x$ with respect to the line $x + y + 4 = 0$. If $d$ denotes the distance between $A$ and $B$, and $a$ denotes the area of $\triangle SAB$, where $S$ is the focus of the parabola $y^2 = 4x$, then the value of $(a + d)$ is _______.
If $y = y(x)$ is the solution of the differential equation, $$\sqrt{4 - x^2} \frac{dy}{dx} = \left(\left(\sin^{-1}\left(\frac{x}{2}\right)\right)^2-y\right)\sin^{-1}\left(\frac{x}{2}\right), -2 \leq x \leq 2, y(2) = \frac{\pi^2 - 8}{4},$$ then $y^2(0)$ is equal to
Answer: 4
Solution
Given $\($ $\frac{dy}{dx}$ + $\left$( $\sin$^{-1} $\frac{x}{2}$ $\right$)^2 y = $\left$( $\sin$^{-3} $\frac{x}{2}$ $\right$)^3 $\frac{\sqrt{4-x^2}}{\sqrt{4-x^2}}$ $\)$. Multiplying both sides by $\($ e^{$\left$( $\sin$^{-1} $\frac{x}{2}$ $\right$)^2} $\)$, we have $$ ye^{\left( \sin^{-1} \frac{x}{2} \right)^2} = \int \left( \sin^{-3} \frac{x}{2} \right)^3 e^{\left( \sin^{-1} \frac{x}{2} \right)^2} \frac{1}{4-x^2} \, dx $$ Thus, $$ y = \left( \sin^{-1} \frac{x}{2} \right)^2 - 2 + c \cdot e^{-\left( \sin^{-1} \frac{x}{2} \right)^2} $$ Given $\($ y(2) = $\frac{\pi^2}{4}$ - 2 $\Rightarrow$ c = 0 $\)$ Therefore, $\($ y(0) = -2 $\)$
Physics
Question 26
Physics · Electromagnetic Induction · Single correct
A uniform magnetic field of $0.4\,\mathrm{T}$ acts perpendicular to a circular copper disc $20\,\mathrm{cm}$ in radius. The disc is having a uniform angular velocity of $10\pi\,\mathrm{rad\,s^{-1}}$ about an axis through its centre and perpendicular to the disc. What is the potential difference developed between the axis of the disc and the rim? $(\pi = 3.14)$
0.5024 V
V
0.2512 V
0.1256 V
Answer: (c)
Solution
Given $B = 0.4 \, \mathrm{T}$, $r = 20 \, \mathrm{cm}$, $\omega = 10 \pi \, \mathrm{rad/s}$. The electromotive force $E$ is given by $$E = \frac{1}{2} B \omega R^2$$ which equals $0.2512 \, \mathrm{V}$.
Question 27
Physics · Electrostatic Potential and Capacitance · Single correct
A parallel plate capacitor of capacitance $1\mu \mathrm{F}$ is charged to a potential difference of $20 \mathrm{V}$. The distance between plates is $1\mu \mathrm{m}$. The energy density between plates of capacitor is.
The kinetic energy of translation of the molecules in 50 $\mathrm{g}$ of $\mathrm{CO_2}$ gas at $17\,^\circ\mathrm{C}$ is
4205.5 $\,$ $\mathrm{J}$
4102.8 $\,$ $\mathrm{J}$
3582.7 $\,$ $\mathrm{J}$
3986.3 $\,$ $\mathrm{J}$
Answer: (b)
Solution
Kinetic energy of translation is given by $\frac{3}{2} nRT$. Given $n = \frac{50 \, \mathrm{g}}{44 \, \mathrm{g}} = \frac{25}{22} \, \mathrm{mol}$ and $T = 17^\circ \mathrm{C} = 290 \, \mathrm{K}$. Therefore, the kinetic energy of translation is $$\frac{3}{2} \left( \frac{25}{22} \right) (8.3)(290) \, \mathrm{J}$$ which equals $4102.8 \, \mathrm{J}$.
Question 31
Physics · Ray Optics and Optical Instruments · Single correct
In a long glass tube, mixture of two liquids A and B with refractive indices 1.3 and 1.4 respectively, forms a convex refractive meniscus towards A. If an object placed at 13 cm from the vertex of the meniscus in A forms an image with a magnification of '-2' then the radius of curvature of meniscus is :
$\frac{1}{3}$ cm
$\frac{4}{3}$ cm
1 cm
$\frac{2}{3}$ cm
Answer: (d)
Solution
Given the refractive indices $n_1 = 1.3$ and $n_2 = 1.4$, and the object distance $u = -13 \, \mathrm{cm}$, we use the lens formula: $$\frac{n_2}{v} - \frac{n_1}{u} = \frac{n_2 - n_1}{R}$$ Substituting the values: $$\frac{1.4}{v} - \frac{1.3}{-13} = \frac{0.1}{R}$$ Simplifying: $$\frac{1.4}{v} = \frac{1}{R} - \frac{1}{10R}$$ $$\frac{1.4}{v} = \frac{10R}{1 - R}$$ The magnification $m$ is given by: $$m = \frac{v/n_2}{u/n_1}$$ Substituting the values: $$-2 \times \frac{-13}{1.3} = \frac{10R}{1 - R}$$ Solving for $R$: $$R = \frac{2}{3} \, \mathrm{cm}$$
Question 32
Physics · Atoms · Single correct
The frequency of revolution of the electron in Bohr's orbit varies with $n$, the principal quantum number as
Which of the following phenomena can not be explained by wave theory of light?
Compton effect
Refraction of light
Reflection of light
Diffraction of light
Answer: (a)
Solution
Compton effect refers to scattering of a photon by free electrons. This phenomenon provides an evidence for particle nature of light.
Question 34
Physics · Motion in a Straight Line · Single correct
The velocity-time graph of an object moving along a straight line is shown in figure. What is the distance covered by the object between $t = 0$ to $t = 4 \, \mathrm{s}$?
30 m
11 m
10 m
13 m
Answer: (a)
Solution
Distance travelled = displacement when direction of velocity remains constant. Therefore, distance = area. $$Distance = Area$$ $$= \frac{1}{2} (2 \, s + 4 \, s)(10 \, m/s)$$ $$= 30 \, m$$
Question 35
Physics · Magnetism and Matter · Single correct
A bar magnet has total length $2l = 20$ units and the field point $P$ is at a distance $d = 10$ units from the centre of the magnet. If the relative uncertainty of length measurement is $1\%$, then uncertainty of the magnetic field at point $P$ is :
4$\%$
15$\%$
5$\%$
10$\%$
Answer: (a)
Solution
Magnetic field at $P$, $B = \frac{\mu_0 \frac{m}{(2l)}}{4\pi r^3}$, where $m$ is the pole strength. $$\Rightarrow \left( \frac{\Delta B}{B} \times 100 \right) = \left( \frac{\Delta l}{l} \right) \times 100 + 3 \left| \frac{\Delta r}{r} \right| \times 100$$ $$= 1\% + 3\% = 4\%$$
Question 36
Physics · Gravitation · Single correct
Earth has mass 8 times and radius 2 times that of a planet. If the escape velocity from the earth is $11.2 \, \mathrm{km/s}$, the escape velocity in $\mathrm{km/s}$ from the planet will be:
2.8
11.2
5.6
8.4
Answer: (c)
Solution
The escape velocity $V_{escape}$ is given by the formula $$V_{escape} = \sqrt{\frac{2GM}{R}}.$$ For the planet, the escape velocity is $$\left( V_{escape} \right)_{Planet} = \sqrt{\left( \frac{M_P}{M_E} \right) \times \left( \frac{R_E}{R_P} \right)} = \frac{1}{2}.$$ Therefore, $$\left( V_{escape} \right)_{Planet} = \frac{1}{2} \left( V_{escape} \right)_{Earth} = 5.6 \, km/s.$$
Question 37
Physics · Oscillations · Single correct
Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). \ Assertion (A): Knowing initial position $x_0$ and initial momentum $p_0$ is enough to determine the position and momentum at any time $t$ for a simple harmonic motion with a given angular frequency $\omega$. \ Reason (R): The amplitude and phase can be expressed in terms of $x_0$ and $p_0$. \ In the light of the above statements, choose the correct answer from the options given below:
is false but (R) is true
is true but (R) is false
Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
Both (A) and (R) are true and (R) is the correct explanation of (A)
Answer: (d)
Solution
If we express position $x(t) = A \sin(\omega t + \phi)$ then $x_0 = A \sin \phi$. $v_0 = A \omega \cos \phi$ implies $\tan \phi = \frac{\omega x_0}{v_0}$. $$A = \sqrt{x_0^2 + \frac{v_0^2}{\omega^2}}$$ Hence both position and linear momentum of a particle can be expressed as a function of time if we know initial momentum and position.
Question 38
Physics · Ray Optics and Optical Instruments · Single correct
A concave mirror produces an image of an object such that the distance between the object and image is 20 cm. If the magnification of the image is '-3', then the magnitude of the radius of curvature of the mirror is :
30 cm
3.75 cm
15 cm
7.5 cm
Answer: (c)
Solution
Given the magnification $m = -3 = -\frac{u}{v}$. We have $u = -x$ and $v = -3x$. This implies $2x = 20 \, \mathrm{cm}$, so $x = 10 \, \mathrm{cm}$. The focal length $f$ is given by $$f = \frac{uV}{u + V} = \frac{(-10)(-30)}{(-10) + (-30)} = -7.5 \, \mathrm{cm}.$$ Also, $f = -\frac{R}{2}$, so $R = -2f = 15 \, \mathrm{cm}$.
Question 39
Physics · Work, Energy and Power · Single correct
A body of mass $4\,\mathrm{kg}$ is placed on a plane at a point $P$ having coordinate $(3,4)\,\mathrm{m}$. Under the action of force $\vec{F}=(2\hat{i}+3\hat{j})\,\mathrm{N}$, it moves to a new point $Q$ having coordinates $(6,10)\,\mathrm{m}$ in $4\,\mathrm{s}$. The average power and instantaneous power at the end of $4\,\mathrm{s}$ are in the ratio:
Physics · Semiconductor Electronics: Materials, Devices and Simple Circuits · Single correct
In the circuit shown here, assuming threshold voltage of diode is negligibly small, then voltage $V_{AB}$ is correctly represented by:
$V_{AB}$ would be zero at all times
Answer: (d)
Solution
Given $V = V_0 \sin \omega t$. The input waveform is a sinusoidal wave with both positive and negative cycles. The output waveform shows only the negative cycle of the input, indicating a half-wave rectification process.
Question 41
Physics · Moving Charges and Magnetism · Single correct
An infinite wire has a circular bend of radius $a$, and carrying a current $I$ as shown in figure. The magnitude of magnetic field at the origin $O$ of the arc is given by:
For the given circuit, the magnetic field contributions are calculated as follows: The magnetic field due to section (1) is given by: $$B_1 = \frac{\mu_0 i}{4 \pi a} \otimes$$ The magnetic field due to section (2) is given by: $$B_2 = \frac{\mu_0 i}{4 \pi a} \left( \frac{3 \pi}{2} \right) \otimes$$ The magnetic field due to section (3) is: $$B_3 = 0$$ The total magnetic field is: $$B = \frac{\mu_0 i}{4 \pi a} \left( 1 + \frac{3 \pi}{2} \right) \otimes$$
Question 42
Physics · System of Particles and Rotational Motion · Single correct
A uniform rod of mass 250 g having length 100 cm is balanced on a sharp edge at 40 cm mark. A mass of 400 g is suspended at 10 cm mark. To maintain the balance of the rod, the mass to be suspended at 90 cm mark, is
190 g
200 g
300 g
290 g
Answer: (a)
Solution
Given $\tau_{Net} = 0$, we have $ (400 \, \mathrm{g} \times 30) = (250 \, \mathrm{g} \times 10) + (m \, \mathrm{g} \times 50)$. Solving for $m$, $$\frac{12000 - 2500}{50} = \frac{9500}{50}$$ Thus, $M = 190 \, \mathrm{g}$.
Question 43
Physics · Mechanical Properties of Fluids · Single correct
A 400 $\mathrm{g}$ solid cube having an edge of length 10 $\mathrm{cm}$ floats in water. How much volume of the cube is outside the water? (Given: density of water = 1000 $\mathrm{kg \, m^{-3}}$)
1400 $\mathrm{cm^3}$
600 $\mathrm{cm^3}$
4000 $\mathrm{cm^3}$
400 $\mathrm{cm^3}$
Answer: (b)
Solution
Volume of cube inside water $$= \left( \frac{Density of cube}{Density of water} \right) \times Volume of cube$$ Mass of cube $$= Density of water$$ $$= 400 \, gm$$ $$= 1 \, gm/cm^3$$ $$= 400 \, cm^3$$ Volume of cube outside water $$= Volume of cube - Volume of cube inside water$$ $$= 1000 \, cm^3 - 400 \, cm^3$$ $$= 600 \, cm^3$$
Question 44
Physics · Electromagnetic Waves · Single correct
The magnetic field of an E.M. wave is given by $\vec{B} = \left( \frac{\sqrt{3}}{2} \hat{i} + \frac{1}{2} \hat{j} \right) 30 \sin \left[ \omega \left( t - \frac{z}{c} \right) \right]$ (S.I. Units). The corresponding electric field in S.I. units is :
A balloon and its content having mass $M$ is moving up with an acceleration $'a'$. The mass that must be released from the content so that the balloon starts moving up with an acceleration $'3a'$ will be (Take $'g'$ as acceleration due to gravity)
$\frac{2Ma}{3a+g}$
$\frac{3Ma}{2a-g}$
$\frac{3Ma}{2a+g}$
$\frac{2Ma}{3a-g}$
Answer: (a)
Solution
Given the equations: $$F - mg = ma$$ Rearranging gives: $$F = ma + mg$$ For the second scenario: $$F - (m-x)g = (m-x)3a$$ Substitute for $F$: $$Ma + mg - mg + xg = 3ma - 3xa$$ Solving for $x$: $$x = \frac{2ma}{g + 3a}$$
Question 46
Physics · Electromagnetic Induction · Fill in the blank
A conducting bar moves on two conducting rails as shown in the figure. A constant magnetic field $B$ exists into the page. The bar starts to move from the vertex at time $t = 0$ with a constant velocity. If the induced EMF is $E \propto t^n$, then value of $n$ is _.
Answer: 1
Solution
As the bar moves without change in orientation, the length of bar will be proportional to its distance from the vertex. i.e. $I = c(vt)$ induced emf $E = B/v$ $= cBv^2t$ $\Rightarrow n = 1$
Question 47
Physics · Electric Charges and Fields · Fill in the blank
An electric dipole of dipole moment $6 \times 10^{-6} \, \mathrm{Cm}$ is placed in uniform electric field of magnitude $10^6 \, \mathrm{V/m}$. Initially, the dipole moment is parallel to electric field. The work that needs to be done on the dipole to make its dipole moment opposite to the field, will be ____ J.
Answer: 12
Solution
Work done in rotating a dipole $= \Delta U$ $$W = (-PE \cos \theta_f) - (-PE \cos \theta_i)$$ or $$= 2PE (\therefore \theta_f = 180^\circ and \theta_i = 0^\circ)$$ $$= (2 \times 6 \times 10^{-6} \times 10^6) \, \mathrm{J} = 12 \, \mathrm{J}$$
Question 48
Physics · Mechanical Properties of Solids · Numerical
The volume contraction of a solid copper cube of edge length 10 cm, when subjected to a hydraulic pressure of $7 \times 10^6 \, \mathrm{Pa}$, would be ___ $\mathrm{mm}^3$. (Given bulk modulus of copper $= 1.4 \times 10^{11} \, \mathrm{N} \, \mathrm{m}^{-2}$)
Answer: 50
Solution
Given the formula for bulk modulus $B = \frac{\Delta P}{\frac{\Delta V}{V}}$. Calculate $\Delta V$ using the given values: $$\Delta V = \frac{7 \times 10^6}{1.4 \times 10^{11}} \times \left(10 \times 10^{-2}\right)^3$$ Finally, $\Delta V = 50 \, \mathrm{mm}^3$.
Question 49
Physics · Current Electricity · Numerical
The value of current $I$ in the electrical circuit as given below, when potential at $A$ is equal to the potential at $B$, will be ____ A.
Answer: 2
Solution
Given $V_A = V_B$, the bridge is balanced. $$\frac{10}{R} = \frac{20}{40}$$ Solving for $R$: $$R = 20 \, \Omega$$ Calculating the current $I$: $$I = \frac{40}{20} = 2 \, \mathrm{A}$$
Question 50
Physics · Wave Optics · Numerical
A thin transparent film with refractive index 1.4, is held on circular ring of radius 1.8 $\mathrm{cm}$. The fluid in the film evaporates such that transmission through the film at wavelength 560 $\mathrm{nm}$ goes to a minimum every 12 $\mathrm{seconds}$. Assuming that the film is flat on its two sides, the rate of evaporation is $\pi$ $\times{10^{-13}}$ $\mathrm{m^3/s}$.
Answer: 54
Solution
For a thin film interference, a fringe for transmission is formed. When $$2 \mu x = n \lambda$$ Therefore, $$\frac{dx}{dt} = \left( \frac{dn}{dt} \right) \frac{\lambda}{2 \mu}$$ $$= \left( \frac{1}{12} \right) \frac{560 \times 10^{-9}}{2 \times 1.4} = \frac{5}{3} \times 10^{-8} \, \mathrm{m/s}$$ Let $V$ be the volume of the film, then $$V = \pi R^2 x$$ Differentiating with respect to time, $$\frac{dV}{dt} = \pi R^2 \frac{dx}{dt}$$ $$= \pi (1.8 \times 10^{-2})^2 \frac{5}{3} \times 10^{-8} \, \mathrm{m^3/s}$$ $$= 54 \pi \times 10^{-13} \, \mathrm{m^3/s}$$
Chemistry
Question 51
Chemistry · Chemical Kinetics and Nuclear Chemistry · Single correct
Consider an elementary reaction A(g) + B(g) $\rightarrow$ C(g) + D(g) If the volume of reaction mixture is suddenly reduced to $\frac{1}{3}$ of its initial volume, the reaction rate will become ' x ' times of the original reaction rate. The value of x is :
3
$\frac{1}{9}$
9
$\frac{1}{3}$
Answer: (c)
Solution
Since the reaction is elementary, $$Rate = k[A]^1[B]^1$$ When $V$ is reduced to $\frac{1}{3} V$, concentration will be tripled. Hence, $$rate = 9 \times (rate)_{initial}$$ $$x = 9$$
Question 52
Chemistry · The d-and f-Block Elements · Single correct
The amphoteric oxide among $\mathrm{V}_2\mathrm{O}_3$, $\mathrm{V}_2\mathrm{O}_4$ and $\mathrm{V}_2\mathrm{O}_5$, upon reaction with alkali leads to formation of an oxide anion. The oxidation state of V in the oxide anion is:
$+3$
$+4$
$+7$
$+5$
Answer: (d)
Solution
$V_2O_5$ is amphoteric oxide. $V_2O_5$ gives $VO_4^{3-}$ on reaction with alkali. Oxidation state of V in $VO_4^{3-}$ is +5.
Question 53
Chemistry · Co-ordination Compounds · Single correct
Match List - I with List - II. Choose the correct answer from the options given below :
Arrange the following in increasing order of solubility product : $Ca(OH)_2$, $AgBr$, $PbS$, $HgS$
HgS < AgBr < PbS < Ca(OH)_2
Ca(OH)_2 < AgBr < HgS < PbS
PbS < HgS < Ca(OH)_2 < AgBr
HgS < PbS < AgBr < Ca(OH)_2
Answer: (c)
Solution
Based on the Ksp values and salt analysis cation identification, we can say that order of Ksp value is: HgS < PbS < AgBr < $\mathrm{Ca(OH)_2}$ Ksp values HgS $\to$ 4 $\times$ 10^{-53} PbS $\to$ 8 $\times$ 10^{-28} AgBr $\to$ 5 $\times$ 10^{-13} $\mathrm{Ca(OH)_2}$ $\to$ 5.5 $\times$ 10^{-6}
Question 56
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
The purification method based on the following physical transformation is: Solid (X) $\xrightarrow{Heat}$ Vapour (X) $\xrightarrow{Cool}$ Solid (X)
Distillation
Extraction
Sublimation
Crystallization
Answer: (c)
Solution
Phase transfer from solid to vapour directly is known as sublimation.
Question 57
Chemistry · Biomolecules · Single correct
Identify correct conversion during acidic hydrolysis from the following: (A) starch gives galactose. (B) cane sugar gives equal amount of glucose and fructose. (C) milk sugar gives glucose and galactose. (D) amylopectin gives glucose and fructose. (E) amylose gives only glucose. Choose the correct answer from the options given below:
, (B) and (C) only
, (C) and (E) only
, (D) and (E) only
, (C) and (D) only
Answer: (b)
Solution
Q10. (A) Starch $\xrightarrow{H^+/H_2O}$ Glucose (B) Cane sugar $\xrightarrow{H^+/H_2O}$ glucose + fructose (Sucrose) 50$\%$ 50$\%$ (C) Milk sugar $\xrightarrow{H^+/H_2O}$ glucose + galactose (Lactose) (D) Amylopectin $\xrightarrow{H^+/H_2O}$ Glucose (E) Amylose $\xrightarrow{H^+/H_2O}$ Glucose So, correct options are B, C, and E only.
Question 58
Chemistry · Thermodynamics · Single correct
An ideal gas undergoes a cyclic transformation starting from the point A and coming back to the same point by tracing the path $A \to B \to C \to D \to A$ as shown in the three cases above. Choose the correct option regarding $\Delta U$ :
\Delta U (Case-I) = \Delta U (Case-II) = \Delta U (Case-III)
\Delta U (Case-I) > \Delta U (Case-III) > \Delta U (Case-II)
\Delta U (Case-III) > \Delta U (Case-II) > \Delta U (Case-I)
\Delta U (Case-I) > \Delta U (Case-II) > \Delta U (Case-III)
Answer: (c)
Solution
As internal energy $U$ is a state function, its cyclic integral must be zero in a cyclic process. Therefore, $\Delta U$ case (I) = $\Delta U$ case (II) = $\Delta U$ case (III).
Question 59
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
The product $B$ formed in the following reaction sequence is:
Answer: (d)
Solution
Question 60
Chemistry · Some Basic Concepts of Chemistry · Single correct
Concentrated nitric acid is labelled as 75$\%$ by mass. The volume in mL of the solution which contains 30 $\mathrm{g}$ of nitric acid is $\underline{\hspace{3cm}}$. Given : Density of nitric acid solution is 1.25 $\mathrm{g/mL}$.
Chemistry · Co-ordination Compounds · Single correct
Match List - I with List - II. Choose the correct answer from the options given below:
(A)-(I), (B)-(IV), (C)-(III), (D)-(II)
(A)-(I), (B)-(II), (C)-(III), (D)-(IV)
(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
(A)-(III), (B)-(II), (C)-(I), (D)-(IV)
Answer: (d)
Solution
Option (A) $[\mathrm{CoF}_6]^{3-}$: $\mathrm{Co}^{3+} \rightarrow 3d^6$. The hybridization is $sp^3d^2$. Option (B) $[\mathrm{NiCl}_4]^{2-}$: $\mathrm{Ni}^{2+} \rightarrow 3d^8$. The hybridization is $sp^3$. Option (C) $[\mathrm{Co(NH}_3)_6]^{3+}$: $\mathrm{Co}^{3+} \rightarrow 3d^6$. The hybridization is $d^2sp^3$. Option (D) $[\mathrm{Ni(CN)}_4]^{2-}$: $\mathrm{Ni}^{2+} \rightarrow 3d^8$. The hybridization is $dsp^2$.
Question 62
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
The total number of compounds from below when treated with hot $\mathrm{KMnO_4}$ giving benzoic acid is :
6
3
5
4
Answer: (c)
Solution
The compounds having benzylic hydrogen will give benzoic acid on treatment with hot $\mathrm{KMnO_4}$. The compounds shown are:
Question 63
Chemistry · Hydrocarbons · Single correct
The major product of the following reaction is :
2-Phenylhepta-2,5-diene
6-Phenylhepta-2,4-diene
6-Phenylhepta-3,5-diene
2-Phenylhepta-2,4-diene
Answer: (d)
Solution
Question 64
Chemistry · Classification of Elements and Periodicity in Properties · Single correct
Given below are two statements : \ Statement (I): According to the Law of Octaves, the elements were arranged in the increasing order of their atomic number. \ Statement (II): Meyer observed a periodically repeated pattern upon plotting physical properties of certain elements against their respective atomic numbers. \ In the light of the above statements, choose the correct answer from the options given below :
Both Statement (I) and Statement (II) are false.
Both Statement (I) and Statement (II) are true.
Statement (I) is false but Statement (II) is true.
Statement (I) is true but Statement (II) is false.
Answer: (a)
Solution
Law of octaves was arranged in the increasing order of their atomic weight. Lothar Meyer plotted the physical properties such as atomic volume, melting point and boiling point against atomic weight.
Question 65
Chemistry · Chemical Kinetics and Nuclear Chemistry · Single correct
For bacterial growth in a cell culture, growth law is very similar to the law of radioactive decay. Which of the following graphs is most suitable to represent bacterial colony growth? Where $N$ - Number of Bacteria at any time, $N_0$ - Initial number of Bacteria.
Answer: (c)
Solution
Because the number of bacteria initially is $N_0$ and the number of bacteria at any time $t$ is $N$. Since bacterial growth is given as $$N = N_0 e^{Kt}$$ where $K$ is the growth constant for bacterial growth.
Question 66
Chemistry · Structure of Atom · Multiple correct
Which of the following is/are not correct with respect to energy of atomic orbitals of hydrogen atom? $(A)\ 1s<2p<3d<4s$ $(B)\ 1s<2s=2p<3s=3p$ $(C)\ 1s<2s<2p<3s<3p$ $(D)\ 1s<2s<4s<3d$ Choose the correct answer from the options given below :
(A) and ($C$) only
(B) and (D) only
($C$) and (D) only
(A) and (B) only
Answer: (b)
Solution
For single electron species, energy only depends on 'n' (principal quantum number). So energy of $2s = 2p$ and energy of $3d < 4s$.
Question 67
Chemistry · Solutions · Single correct
Assume a living cell with 0.9$\%$ ($\omega$/$\omega$) of glucose solution (aqueous). This cell is immersed in another solution having equal mole fraction of glucose and water. (Consider the data upto first decimal place only) The cell will :
shrink since solution is 0.45$\%$ ($\omega$/$\omega$) as a result of association of glucose molecules (due to hydrogen bonding)
Show no change in volume since solution is 0.9$\%$ ($\omega$/$\omega$)
swell up since solution is 1$\%$ ($\omega$/$\omega$)
shrink since solution is 0.5$\%$ ($\omega$/$\omega$)
Answer: (d)
Solution
Living cell = 0.9 gm in 100 gm of solution. $\n$ %w/w = 0.9. $\n$ Solution is have equal moles of glucose and water = 0.5. $\n$ Weight of solution = 0.5 $\times$ 180 + 0.5 $\times$ 18 = 99 gm $\;$ $\%$w/w $\simeq$ 90$\%$. $\n$ Concentrated solution = Cell will shrink.
Question 68
Chemistry · Amines · Single correct
Identify the correct statements: \ (A) Primary amines do not give diazonium salts when treated with $\mathrm{NaNO_2}$ in acidic medium. \ (B) Aliphatic and aromatic primary amines on heating with $\mathrm{CHCl_3}$ and ethanolic $\mathrm{KOH}$ form carbylamines. \ (C) Secondary and tertiary amines also give the carbylamine test. \ (D) Benzenesulfonyl chloride is known as Hinsberg's reagent. \ (E) Tertiary amines react with benzenesulfonyl chloride very easily. \ Choose the correct answer from the options given below:
and (B) only
and (E) only
and (D) only
and (C) only
Answer: (c)
Solution
(C) Only primary amine gives carbyl amine test. (D) $\mathrm{Ph - SO_2Cl}$ is the Hinsberg reagent, benzene sulphonyl chloride. (E) Tertiary amine do not react with $\mathrm{Ph - SO_2Cl}$. So correct options are (B) and (D) only.
Question 69
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Given below are two statements: In the light of the above statements, choose the correct answer from the options given below :
Both Statement (I) and Statement (II) are false.
Both Statement (I) and Statement (II) are true.
Statement (I) is false but Statement (II) is true.
Statement (I) is true but Statement (II) is false.
Answer: (b)
Solution
Statement-I is true. Both are ring chain isomers. Statement-II is true. $1^\circ$ Amine and $2^\circ$ Amine are different functional groups, hence both are functional group isomers.
Question 70
Chemistry · Analytical Chemistry · Single correct
Identify the inorganic sulphides that are yellow in colour: \ (A) $\mathrm{(NH_4)_2S}$ \ (B) $\mathrm{PbS}$ \ (C) $\mathrm{CuS}$ \ (D) $\mathrm{As_2S_3}$ \ (E) $\mathrm{As_2S_5}$ \ Choose the correct answer from the options given below:
, (D) and (E) only
and (E) only
and (B) only
and ($C$) only
Answer: (b)
Solution
As$_2$S$_3$ and As$_2$S$_5$ are yellow colour sulphides, (NH$_4$)$_2$S is colourless, PbS is black, CuS is black in colour.
Question 71
Chemistry · The d-and f-Block Elements · Numerical
The spin only magnetic moment ( $\mu$ ) value (B.M.) of the compound with strongest oxidising power among $\mathrm{Mn_2O_3}$, $\mathrm{TiO}$ and $\mathrm{VO}$ is ____ B.M. (Nearest integer).
Answer: 5
Solution
Strongest oxidising power among the option is $\mathrm{Mn_2O_3}$ because of $E^\circ$ value. $$E^\circ_{\mathrm{Mn^{+3}/Mn^{+2}}} = +1.57 \, \mathrm{V}$$ $\mathrm{Mn^{+3}} \rightarrow d^4$ configuration $$\mu = \sqrt{24} \, \mathrm{BM}$$ $$= 4.89 \, \mathrm{BM}$$ $$\Rightarrow 5$$
Question 72
Chemistry · Thermodynamics · Fill in the blank
Consider the following data: Heat of formation of $\mathrm{CO}_2(\mathrm{g}) = -393.5 \, \mathrm{kJ} \, \mathrm{mol}^{-1}$ Heat of formation of $\mathrm{H}_2\mathrm{O}(\mathrm{l}) = -286.0 \, \mathrm{kJ} \, \mathrm{mol}^{-1}$ Heat of combustion of benzene $= -3267.0 \, \mathrm{kJ} \, \mathrm{mol}^{-1}$ The heat of formation of benzene is $\_ \, \mathrm{kJ} \, \mathrm{mol}^{-1}$. (Nearest integer)
Electrolysis of 600 $\mathrm{mL}$ aqueous solution of $\mathrm{NaCl}$ for 5 $\mathrm{min}$ changes the $\mathrm{pH}$ of the solution to 12. The current in Amperes used for the given electrolysis is ____. (Nearest integer).
Answer: 2
Solution
Electrolysis of NaCl is NaCl + $\mathrm{H_2O(aq)}$ $\rightarrow$ $\mathrm{NaOH(aq)}$ + $\frac{1}{2}$ $\mathrm{Cl_2(g)}$ + $\frac{1}{2}$ $\mathrm{H_2(g)}$ Since during electrolysis pH changes to 12 So $[\mathrm{OH}^-] = 10^{-2}$ and $[\mathrm{H}^+] = 10^{-12}$ So by Faraday law Gram amount of substance deposited = Amount of electricity passed $$10^{-2} \times \frac{600}{1000} \times 96500 = I \times t$$ $$10^{-2} \times \frac{600}{1000} \times 96500 = I \times 5 \times 60$$ $$I = \frac{10^{-2} \times 600 \times 96500}{1000 \times 5 \times 60}$$ $I = 1.93$ ampere So, $I = 2$ ampere (nearest integer)
Question 74
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Numerical
A group 15 element forms $d\pi - d\pi$ bond with transition metals. It also forms hydride, which is a strongest base among the hydrides of other group members that form $d\pi - d\pi$ bond. The atomic number of the element is ____.
Answer: 15
Solution
Phosphorus belongs to the $15^{th}$ group and forms $d\pi - d\pi$ bond with transition metal and $\mathrm{PH_3}$ is the strongest base among the other group members except $\mathrm{NH_3}$.
Question 75
Chemistry · Chemical Bonding and Molecular Structure · Numerical
Total number of paramagnetic molecules/species among the following is: $\mathrm{O_2},\ \mathrm{O_2^+},\ \mathrm{O_2^-},\ \mathrm{NO},\ \mathrm{NO_2},\ \mathrm{CO},\ \mathrm{K_2[NiCl_4]},\ \mathrm{[Co(NH_3)_6]Cl_3},\ \mathrm{K_2[Ni(CN)_4]}$.
Answer: 6
Solution
Q11. $\mathrm{O_2} \rightarrow 2$ unpaired electrons according to MOT. $\mathrm{O_2^+} \rightarrow 1$ unpaired electron according to MOT. $\mathrm{O_2^-} \rightarrow 1$ unpaired electron according to MOT. NO $\rightarrow$ odd electron species. $\mathrm{NO_2} \rightarrow$ odd electron species. $\mathrm{K_2[NiCl_4]} \rightarrow \mathrm{Ni^{2+}} \Rightarrow 3\, d^8$ weak Ligand, C.N. $= 4$. $\Rightarrow$ Tetrahedral, Paramagnetic with 2 unpaired electrons.