JEE Main 29 January 2024 Shift 2 question paper with solutions
JEE Main 29 January 2024 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 · Matrices · Single correct
Let $A = \begin{bmatrix} 2 & 1 & 2 \\ 6 & 2 & 11 \\ 3 & 3 & 2 \end{bmatrix}$ and $P = \begin{bmatrix} 1 & 2 & 0 \\ 5 & 0 & 2 \\ 7 & 1 & 5 \end{bmatrix}$. The sum of the prime factors of $|P^{-1}AP - 2I|$ is equal to
26
27
66
23
Answer: (a)
Solution
Given $|P^{-1}AP - 2I| = |P^{-1}AP - 2P^{-1}P|$. This equals $|P^{-1}(A - 2I)P|$. Using the property of determinants, this becomes $|P^{-1}||A - 2I||P|$. Since $|P^{-1}| = 1/|P|$, it simplifies to $|A - 2I|$. Calculating the determinant: $$\begin{vmatrix} 0 & 1 & 2 \\ 6 & 0 & 11 \\ 3 & 3 & 0 \end{vmatrix} = 69$$ So, the prime factors of 69 are 3 and 23. Thus, the sum is 26.
Question 2
Maths · Permutations and Combinations · Single correct
Number of ways of arranging 8 identical books into 4 identical shelves where any number of shelves may remain empty is equal to
Maths · Three Dimensional Geometry · Single correct
Let P(3, 2, 3), Q(4, 6, 2) and R(7, 3, 2) be the vertices of $\triangle$ PQR. Then, the angle $\angle$ QPR is
$\frac{\pi}{6}$
$\cos^{-1}\left(\frac{7}{18}\right)$
$\cos^{-1}\left(\frac{1}{18}\right)$
$\frac{\pi}{3}$
Answer: (d)
Solution
Direction ratio of PR = (4, 1, -1). Direction ratio of PQ = (1, 4, -1). Now, $\($ $\cos$ $\theta$ = $\left$| $\frac{4 + 4 + 1}{\sqrt{18} \cdot \sqrt{18}}$ $\right$| $\)$. $\($ $\theta$ = $\frac{\pi}{3}$ $\)$.
Question 4
Maths · Statistics · Single correct
If the mean and variance of five observations are $\frac{24}{5}$ and $\frac{194}{25}$ respectively and the mean of first four observations is $\frac{7}{2}$, then the variance of the first four observations in equal to
$\frac{4}{5}$
$\frac{77}{12}$
$\frac{5}{4}$
$\frac{105}{4}$
Answer: (c)
Solution
Given $\bar{X} = \frac{24}{5}$; $\sigma^2 = \frac{194}{25}$. Let first four observations be $x_1, x_2, x_3, x_4$. Here, $$\frac{x_1 + x_2 + x_3 + x_4 + x_5}{5} = \frac{24}{5} \cdots$$ Also, $$\frac{x_1 + x_2 + x_3 + x_4}{4} = \frac{7}{2}$$ which implies $$x_1 + x_2 + x_3 + x_4 = 14.$$ Now from equation 1, $x_5 = 10$. Now, $\sigma^2 = \frac{194}{25}$. $$\frac{x_1^2 + x_2^2 + x_3^2 + x_4^2 + x_5^2}{5} - \frac{576}{25} = \frac{194}{25}$$ which implies $$x_1^2 + x_2^2 + x_3^2 + x_4^2 = 54.$$ Now, variance of first 4 observations $$Var = \frac{\sum_{i=1}^{4} x_i^2}{4} - \left(\frac{\sum_{i=1}^{4} x_i}{4}\right)^2$$ $$= \frac{54}{4} - \frac{49}{4} = \frac{5}{4}.$$
Question 5
Maths · Applications of Derivatives · Single correct
The function $f(x) = 2x + 3(x)^{\frac{2}{3}}, x \in \mathbb{R}$, has
exactly one point of local minima and no point of local maxima
exactly one point of local maxima and no point of local minima
exactly one point of local maxima and exactly one point of local minima
exactly two points of local maxima and exactly one point of local minima
Answer: (c)
Solution
Given $f(x) = 2x + 3(x)^{\frac{2}{3}}$. The derivative is $f'(x) = 2 + 2x^{-\frac{1}{3}}$. This can be rewritten as: $$= 2 \left( 1 + \frac{1}{x^{\frac{1}{3}}} \right)$$ $$= 2 \left( \frac{x^{\frac{1}{3}} + 1}{x^{\frac{1}{3}}} \right)$$ The sign chart shows: - Positive for $x 0$ So, maxima (M) at $x = -1$ and minima (m) at $x = 0$.
Question 6
Maths · Complex Numbers and Quadratic Equations · Single correct
Let $r$ and $\theta$ respectively be the modulus and amplitude of the complex number $z = 2 - i \left( 2 \tan \frac{5\pi}{8} \right)$, then $(r, \theta)$ is equal to
The sum of the solutions $x \in \mathbb{R}$ of the equation $$\frac{3 \cos 2x + \cos^3 2x}{\cos^6 x - \sin^6 x} = x^3 - x^2 + 6$$ is
0
1
-1
3
Answer: (c)
Solution
Given $\($ $\frac{3 \cos 2x + \cos^3 2x}{\cos^6 x - \sin^6 x}$ = x^3 - x^2 + 6 $\)$. This implies $$ \frac{\cos 2x \left( 3 + \cos^2 2x \right)}{\cos 2x \left( 1 - \sin^2 x \cos^2 x \right)} = x^3 - x^2 + 6 $$ which simplifies to $$ \frac{4 \left( 3 + \cos^2 2x \right)}{\left( 4 - \sin^2 2x \right)} = x^3 - x^2 + 6 $$ Further simplifying gives $$ \frac{4 \left( 3 + \cos^2 2x \right)}{\left( 3 + \cos^2 2x \right)} = x^3 - x^2 + 6 $$ Thus, $$ x^3 - x^2 + 2 = 0 \Rightarrow (x + 1) \left( x^2 - 2x + 2 \right) = 0 $$ So, the sum of real solutions is $\($-1$\)$.
Question 8
Maths · Vector Algebra · Single correct
Let $\overrightarrow{OA} = \overrightarrow{a}$, $\overrightarrow{OB} = 12 \overrightarrow{a} + 4 \overrightarrow{b}$ and $\overrightarrow{OC} = \overrightarrow{b}$, where O is the origin. If S is the parallelogram with adjacent sides OA and OC, then $$ \frac{\text{area of the quadrilateral OABC}}{\text{area of S}} $$ is equal to
If $\log_e a$, $\log_e b$, $\log_e c$ are in an A.P. and $\log_e a - \log_e 2b$, $\log_e 2b - \log_e 3c$, $\log_e 3c - \log_e a$ are also in an A.P., then $a : b : c$ is equal to
9 : 6 : 4
16 : 4 : 1
25 : 10 : 4
6 : 3 : 2
Answer: (a)
Solution
Given $\log_e a$, $\log_e b$, $\log_e c$ are in A.P. Therefore, $b^2 = ac \ldots (i)$ Also $\log_e \left( \frac{a}{2b} \right)$, $\log_e \left( \frac{2b}{3c} \right)$, $\log_e \left( \frac{3c}{a} \right)$ are in A.P. $$\left( \frac{2b}{3c} \right)^2 = \frac{a}{2b} \times \frac{3c}{a}$$ $$\frac{b}{c} = \frac{3}{2}$$ Putting in eq. (i) $b^2 = a \times \frac{2b}{3}$ $$\frac{a}{b} = \frac{3}{2}$$ $a : b : c = 9 : 6 : 4$
Question 10
Maths · Integrals · Single correct
If $$\int \frac{\sin^{\frac{3}{2}} x + \cos^{\frac{3}{2}} x}{\sqrt{\sin^3 x \cos^3 x \sin(x - \theta)}} \, dx = A\sqrt{\cos\theta\tan x-\sin\theta} +B\sqrt{\cos\theta-\sin\theta\cot x} +C$$ where C is the integration constant, then AB is equal to
4 $\csc$(2$\theta$)
4 $\sec$ $\theta$
2 $\sec$ $\theta$
8 $\csc$(2$\theta$)
Answer: (d)
Solution
Given $$\int \frac{\sin^{\frac{3}{2}} x + \cos^{\frac{3}{2}} x}{\sqrt{\sin^3 x \cos^3 x \sin(x - \theta)}} \, dx$$ Let $$I = \int \frac{\sin^{\frac{3}{2}} x + \cos^{\frac{3}{2}} x}{\sqrt{\sin^3 x \cos^3 x (\sin x \cos \theta - \cos x \sin \theta)}} \, dx$$ This can be rewritten as: $$= \int \frac{\sin^{\frac{3}{2}} x}{\sin^{\frac{3}{2}} x \cos^2 x \sqrt{\tan x \cos \theta - \sin \theta}} \, dx + \int \frac{\cos^{\frac{3}{2}} x}{\sin^2 x \cos^{\frac{3}{2}} x \sqrt{\cos \theta - \cot x \sin \theta}} \, dx$$ Let $$I = I_1 + I_2$$ For $I_1$, let $\tan x \cos \theta - \sin \theta = t^2$ Then $$\sec^2 x \, dx = \frac{2t \, dt}{\cos \theta}$$ For $I_2$, let $\cos \theta - \cot x \sin \theta = z^2$ Then $$\csc^2 x \, dx = \frac{2z \, dz}{\sin \theta}$$ Thus, $$I = I_1 + I_2$$ This becomes: $$= \int \frac{2t \, dt}{\cos \theta} + \int \frac{2z \, dz}{\sin \theta}$$ Simplifying gives: $$= \frac{2t}{\cos \theta} + \frac{2z}{\sin \theta}$$ Finally, $$= 2 \sec \theta \sqrt{\tan x \cos \theta - \sin \theta} + 2 \csc \theta \sqrt{\cos \theta - \cot x \sin \theta}$$ Comparing, we have $$AB = 8 \csc 2\theta$$
Question 11
Maths · Straight Lines and Pair of Straight Lines · Single correct
The distance of the point $(2, 3)$ from the line $2x - 3y + 28 = 0$, measured parallel to the line $\sqrt{3}x - y + 1 = 0$, is equal to
$4\sqrt{2}$
$6\sqrt{3}$
$3 + 4\sqrt{2}$
$4 + 6\sqrt{3}$
Answer: (d)
Solution
Writing P in terms of parametric coordinates $2 + r \cos \theta, 3 + r \sin \theta$ as $\tan \theta = \sqrt{3}$ $$P \left( 2 + \frac{r}{2}, 3 + \frac{\sqrt{3}r}{2} \right)$$ P must satisfy $2x - 3y + 28 = 0$ So, $2 \left( 2 + \frac{r}{2} \right) - 3 \left( 3 + \frac{\sqrt{3}r}{2} \right) + 28 = 0$ We find $r = 4 + 6\sqrt{3}$
Question 12
Maths · Differential Equations · Single correct
If $\sin\left(\frac{y}{x}\right) = \log_e \left|x\right| + \frac{\alpha}{2}$ is the solution of the differential equation $x \cos\left(\frac{y}{x}\right) \frac{dy}{dx} = y \cos\left(\frac{y}{x}\right) + x$ and $y(1) = \frac{\pi}{3}$, then $\alpha^2$ is equal to
3
12
4
9
Answer: (a)
Solution
Differential equation: $$x \cos \frac{y}{x} \frac{dy}{dx} = y \cos \frac{y}{x} + x$$ $$\cos \frac{y}{x} \left[ x \frac{dy}{dx} - y \right] = x$$ Divide both sides by $x^2$ $$\cos \frac{y}{x} \left( \frac{x \frac{dy}{dx} - y}{x^2} \right) = \frac{1}{x}$$ Let $\frac{y}{x} = t$ $$\cos t \left( \frac{dt}{dx} \right) = \frac{1}{x}$$ $$\cos t \, dt = \frac{1}{x} \, dx$$ Integrating both sides $$\sin t = \ln |x| + c$$ $$\sin \frac{y}{x} = \ln |x| + c$$ Using $y(1) = \frac{\pi}{3}$, we get $c = \frac{\sqrt{3}}{2}$ So, $\alpha = \sqrt{3} \Rightarrow \alpha^2 = 3$
Question 13
Maths · Sequences and Series · Single correct
If each term of a geometric progression $a_1, a_2, a_3, \ldots$ with $a_1 = \frac{1}{8}$ and $a_2 \neq a_1$, is the arithmetic mean of the next two terms and $S_n = a_1 + a_2 + \ldots + a_n$, then $S_{20} - S_{18}$ is equal to
$2^{15}$
$-2^{18}$
$2^{18}$
$-2^{15}$
Answer: (d)
Solution
Let $r$'th term of the GP be $ar^{n-1}$. Given, $$2a_r = a_{r+1} + a_{r+2}$$ $$2ar^{n-1} = ar^n + ar^{n+1}$$ $$\frac{2}{r} = 1 + r$$ $$r^2 + r - 2 = 0$$ Hence, we get $r = -2$ (as $r \neq 1$). So, $S_{20} - S_{18} = (\text{Sum up to 20 terms}) - (\text{Sum up to 18 terms}) = T_{19} + T_{20}$ $$T_{19} + T_{20} = ar^{18}(1+r)$$ Putting the values $a = \dfrac{1}{8}$ and $r = -2$: $$T_{19} + T_{20} = -2^{15}$$
Question 14
Maths · Straight Lines and Pair of Straight Lines · Single correct
Let A be the point of intersection of the lines $3x + 2y = 14$, $5x - y = 6$ and B be the point of intersection of the lines $4x + 3y = 8$, $6x + y = 5$. The distance of the point $P(5, -2)$ from the line AB is
$\frac{13}{2}$
8
$\frac{5}{2}$
6
Answer: (d)
Solution
Solving lines $L_1(3x + 2y = 14)$ and $L_2(5x - y = 6)$ to get $A(2, 4)$ and solving lines $L_3(4x + 3y = 8)$ and $L_4(6x + y = 5)$ to get $B\left(\frac{1}{2}, 2\right)$. Finding Eqn. of $AB : 4x - 3y + 4 = 0$. Calculate distance $PM$ $$\Rightarrow \left| \frac{4(5) - 3(-2) + 4}{5} \right| = 6$$
Question 15
Maths · Inverse Trigonometric Functions · Single correct
Let $x = \frac{m}{n}$ (m, n are co-prime natural numbers) be a solution of the equation $\cos \left( 2 \sin^{-1} x \right) = \frac{1}{9}$ and let $\alpha, \beta (\alpha > \beta)$ be the roots of the equation $mx^2 - nx - m + n = 0$. Then the point $(\alpha, \beta)$ lies on the line
3x + 2y = 2
5x - 8y = -9
3x - 2y = -2
5x + 8y = 9
Answer: (d)
Solution
Assume $\sin^{-1} x = \theta$. $$\cos(2\theta) = \frac{1}{9}$$ $$\sin \theta = \pm \frac{2}{3}$$ As $m$ and $n$ are co-prime natural numbers, $$x = \frac{2}{3}$$ i.e. $m = 2$, $n = 3$. So, the quadratic equation becomes $2x^2 - 3x + 1 = 0$ whose roots are $\alpha = 1$, $\beta = \frac{1}{2} \left(1, \frac{1}{2}\right)$ lies on $$5x + 8y = 9$$
Question 16
Maths · Applications of Derivatives · Single correct
The function $f(x) = \frac{x}{x^2 - 6x - 16}$, $x \in \mathbb{R} - \{-2, 8\}$
decreases in $(-2, 8)$ and increases in $(-\infty, -2) \cup (8, \infty)$
decreases in $(-\infty, -2) \cup (-2, 8)$
decreases in $(-\infty, -2)$ and increases in $(8, \infty)$
increases in $(-\infty, -2) \cup (-2, 8) \cup (8, \infty)$
If R is the smallest equivalence relation on the set {$1, 2, 3, 4$\} such that $\{$(1,2), (1,3)$\} \subseteq$ R, then the number of elements in R is $\ldots$
10
12
8
15
Answer: (a)
Solution
Question 19
Maths · Probability · Single correct
An integer is chosen at random from the integers 1, 2, 3, $\ldots$, 50. The probability that the chosen integer is a multiple of atleast one of 4, 6 and 7 is
$\frac{8}{25}$
$\frac{21}{50}$
$\frac{9}{50}$
$\frac{14}{25}$
Answer: (b)
Solution
Given set = {1, 2, 3, $\ldots$, 50$\}$ P(A) = Probability that number is multiple of 4 $P(B)$ = Probability that number is multiple of 6 $P(C)$ = Probability that number is multiple of 7 Now, $$P(A) = \frac{12}{50}, \; P(B) = \frac{8}{50}, \; P(C) = \frac{7}{50}$$ again $$P(A \cap B) = \frac{4}{50}, \; P(B \cap C) = \frac{1}{50}, \; P(A \cap C) = \frac{1}{50}$$ $$P(A \cap B \cap C) = 0$$ Thus $$P(A \cup B \cup C) = \frac{12}{50} + \frac{8}{50} + \frac{7}{50} - \frac{4}{50} - \frac{1}{50} - \frac{1}{50} + 0$$ $$= \frac{21}{50}$$
Question 20
Maths · Vector Algebra · Single correct
Let a unit vector $\hat{u} = x \hat{i} + y \hat{j} + z \hat{k}$ make angles $\frac{\pi}{2}$, $\frac{\pi}{3}$ and $\frac{2\pi}{3}$ with the vectors $\frac{1}{\sqrt{2}} \hat{i} + \frac{1}{\sqrt{2}} \hat{k}$, $\frac{1}{\sqrt{2}} \hat{j} + \frac{1}{\sqrt{2}} \hat{k}$ and $\frac{1}{\sqrt{2}} \hat{i} + \frac{1}{\sqrt{2}} \hat{j}$ respectively. If $\vec{v} = \frac{1}{\sqrt{2}} \hat{i} + \frac{1}{\sqrt{2}} \hat{j} + \frac{1}{\sqrt{2}} \hat{k}$, then $|\hat{u} - \vec{v}|^2$ is equal to
$\frac{11}{2}$
$\frac{5}{2}$
9
7
Answer: (b)
Solution
Unit vector $\mathbf{\hat{u}} = x \mathbf{\hat{i}} + y \mathbf{\hat{j}} + z \mathbf{\hat{k}}$. $$\mathbf{P}_1 = \frac{1}{\sqrt{2}} \mathbf{\hat{i}} + \frac{1}{\sqrt{2}} \mathbf{\hat{k}}, \mathbf{P}_2 = \frac{1}{\sqrt{2}} \mathbf{\hat{j}} + \frac{1}{\sqrt{2}} \mathbf{\hat{k}}$$ $$\mathbf{P}_3 = \frac{1}{\sqrt{2}} \mathbf{\hat{i}} + \frac{1}{\sqrt{2}} \mathbf{\hat{j}}$$ Now angle between $\mathbf{\hat{u}}$ and $\mathbf{P}_1 = \frac{\pi}{2}$. $$\mathbf{\hat{u}} \cdot \mathbf{P}_1 = 0 \Rightarrow \frac{x}{\sqrt{2}} + \frac{z}{\sqrt{2}} = 0$$ $$\Rightarrow x + z = 0 \ldots (i)$$ Angle between $\mathbf{\hat{u}}$ and $\mathbf{P}_2 = \frac{\pi}{3}$. $$\mathbf{\hat{u}} \cdot \mathbf{P}_2 = |\mathbf{\hat{u}}| \cdot |\mathbf{P}_2| \cos \frac{\pi}{3}$$ $$\Rightarrow \frac{y}{\sqrt{2}} + \frac{z}{\sqrt{2}} = \frac{1}{2} \Rightarrow y + z = \frac{1}{\sqrt{2}} \ldots (ii)$$ Angle between $\mathbf{\hat{u}}$ and $\mathbf{P}_3 = \frac{2\pi}{3}$. $$\mathbf{\hat{u}} \cdot \mathbf{P}_3 = |\mathbf{\hat{u}}| \cdot |\mathbf{P}_3| \cos \frac{2\pi}{3}$$ $$\Rightarrow \frac{x}{\sqrt{2}} + \frac{4}{\sqrt{2}} = -\frac{1}{2} \Rightarrow x + y = \frac{-1}{\sqrt{2}} \ldots (iii)$$ From equation (i), (ii) and (iii) we get $$x = -\frac{1}{\sqrt{2}}, y = 0, z = \frac{1}{\sqrt{2}}$$ Thus $\mathbf{\hat{u}} - \mathbf{\hat{v}} = -\frac{1}{\sqrt{2}} \mathbf{\hat{i}} + \frac{1}{\sqrt{2}} \mathbf{\hat{k}} - \frac{1}{\sqrt{2}} \mathbf{\hat{i}} - \frac{1}{\sqrt{2}} \mathbf{\hat{j}} - \frac{1}{\sqrt{2}} \mathbf{\hat{k}}$ $$\mathbf{\hat{u}} - \mathbf{\hat{v}} = \frac{-2}{\sqrt{2}} \mathbf{\hat{i}} - \frac{1}{\sqrt{2}} \mathbf{\hat{j}}$$ $$\therefore |\mathbf{\hat{u}} - \mathbf{\hat{v}}|^2 = \left( \sqrt{\frac{4}{2} + \frac{1}{2}} \right)^2 = \frac{5}{2}$$
Question 21
Maths · Complex Numbers and Quadratic Equations · Numerical
Let $\alpha$, $\beta$ be the roots of the equation $x^2 - \sqrt{6}x + 3 = 0$ such that $\mathrm{Im}(\alpha) > \mathrm{Im}(\beta)$. Let $a, b$ be integers not divisible by 3 and $n$ be a natural number such that $\frac{\alpha^{99}}{\beta} + \alpha^{98} = 3^n (a + ib)$, $i = \sqrt{-1}$. Then $n + a + b$ is equal to ______.
Answer: 49
Solution
Given the equation $x^2 - \sqrt{6}x + 6 = 0$, we have roots $\alpha$ and $\beta$. The roots are given by $$x = \frac{\sqrt{6} \pm i \sqrt{6}}{2} = \frac{\sqrt{6}}{2} (1 \pm i).$$ Thus, $$\alpha = \sqrt{3} \left( e^{i \frac{\pi}{4}} \right), \beta = \sqrt{3} \left( e^{-i \frac{\pi}{4}} \right).$$ Therefore, $$\frac{\alpha^{99}}{\beta} + \alpha^{98} = \alpha^{98} \left( \frac{\alpha}{\beta} + 1 \right).$$ This simplifies to $$\frac{\alpha^{98}(\alpha + \beta)}{\beta} = 3^{49} \left( e^{i 99 \frac{\pi}{4}} \right) \times \sqrt{2}.$$ Thus, $$3^{49} (-1 + i) = 3^n (a + ib).$$ So, $n = 49$, $a = -1$, $b = 1$. Finally, $n + a + b = 49 - 1 + 1 = 49.$
Question 22
Maths · Determinants · Numerical
Let for any three distinct consecutive terms $a$, $b$, $c$ of an A.P., the lines $ax + by + c = 0$ be concurrent at the point $P$ and $Q(\alpha, \beta)$ be a point such that the system of equations $$x + y + z = 6,$$ $$2x + 5y + \alpha z = \beta$$ and $$x + 2y + 3z = 4,$$ has infinitely many solutions. Then $(PQ)^2$ is equal to
Answer: 113
Solution
Given $a, b, c$ are in A.P. Therefore, $2b = a + c \Rightarrow a - 2b + c = 0$. Thus, $ax + by + c$ passes through the fixed point $(1, -2)$. Therefore, $P = (1, -2)$. For infinite solution, $D = D1 = D2 = D3 = 0$. $$D : \begin{vmatrix} 1 & 1 & 1 \\ 2 & 5 & \alpha \\ 1 & 2 & 3 \end{vmatrix} = 0$$ This implies $\alpha = 8$. $$D_1 : \begin{vmatrix} 6 & 1 & 1 \\ \beta & 5 & \alpha \\ 4 & 2 & 3 \end{vmatrix} = 0 \Rightarrow \beta = 6$$ Therefore, $Q = (8, 6)$. Thus, $PQ^2 = 113$.
Question 23
Maths · Conic Sections · Numerical
Let P($\alpha$, $\beta$) be a point on the parabola $y^2 = 4x$. If P also lies on the chord of the parabola $x^2 = 8y$ whose mid point is $\left(1, \frac{5}{4}\right)$. Then $(\alpha - 28)(\beta - 8)$ is equal to .
If $\int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \sqrt{1-\sin 2x}\,dx=\alpha+\beta\sqrt{2}+\gamma\sqrt{3}$, where $\alpha$, $\beta$ and $\gamma$ are rational numbers, then $3\alpha+4\beta-\gamma$ is equal to _______
Answer: 6
Solution
The integral from $\frac{\pi}{6}$ to $\frac{\pi}{3}$ of $\sqrt{1 - \sin 2x} \, dx$ is evaluated as follows: $$= \int_{\frac{\pi}{6}}^{\frac{\pi}{3}} \sin x - \cos x \, dx$$ This can be split into two integrals: $$= \int_{\frac{\pi}{6}}^{\frac{\pi}{4}} (\cos x - \sin x) \, dx + \int_{\frac{\pi}{4}}^{\frac{\pi}{3}} (\sin x - \cos x) \, dx$$ Evaluating these integrals gives: $$= -1 + 2\sqrt{2} - \sqrt{3}$$ This can be expressed as: $$= \alpha + \beta \sqrt{2} + \gamma \sqrt{3}$$ Where $\alpha = -1$, $\beta = 2$, $\gamma = -1$. Finally, we have: $$3\alpha + 4\beta - \gamma = 6$$
Question 25
Maths · Applications of Integrals · Numerical
Let the area of the region $\{(x, y) : 0 \leq x \leq 3, 0 \leq y \leq \min \{x^2 + 2, 2x + 2\}\}$ be $A$. Then $12A$ is equal to
Answer: 164
Solution
The area is given by the integral: $$A = \int_{0}^{2} (x^2 + 2) \, dx + \int_{2}^{3} (2x + 2) \, dx$$ Calculating the integrals, we find: $$A = \frac{41}{3}$$ Therefore, multiplying by 12 gives: $$12A = 41 \times 4 = 164$$
Question 26
Maths · Three Dimensional Geometry · Numerical
Let O be the origin, and M and N be the points on the lines $\frac{x-5}{4} = \frac{y-4}{1} = \frac{z-5}{3}$ and $\frac{x+8}{12} = \frac{y+2}{5} = \frac{z+11}{9}$ respectively such that MN is the shortest distance between the given lines. Then $\overrightarrow{OM} \cdot \overrightarrow{ON}$ is equal to .
Maths · Continuity and Differentiability · Numerical
Let $f(x) = \sqrt{\lim_{r \to x} \left\{ \frac{2r^2[(f(r))^2 - f(x)f(r)]}{r^2 - x^2} - r^3 e^{\frac{f(r)}{r}} \right\}}$ be differentiable in $(-\infty, 0) \cup (0, \infty)$ and $f(1) = 1$. Then the value of $a$, such that $f(a) = 0$, is equal to ______.
Answer: 2
Solution
Given $f(1) = 1$, $f(a) = 0$. $$f^2(x) = \lim_{r \to x} \left( \frac{2r^2 \left( f^2(r) - f(x)f(r) \right)}{r^2 - x^2} - r^3 e^{\frac{f(x)}{r}} \right)$$ $$= \lim_{r \to x} \left( \frac{2r^2 f(r)}{r + x} \frac{(f(r) - f(x))}{r - x} - r^3 e^{\frac{f(x)}{r}} \right)$$ $$f^2(x) = \frac{2x^2 f(x)}{2x} f'(x) - x^3 e^{\frac{f(x)}{x}}$$ $$y^2 = xy \frac{dy}{dx} - x^3 e^{\frac{y}{x}}$$ $$\frac{y}{x} \frac{dy}{dx} - \frac{x^2}{y} e^{\frac{y}{x}}$$ Put $y = vx$ then $\frac{dy}{dx} = v + x \frac{dv}{dx}$. $$v = v + x \frac{dv}{dx} - \frac{x}{v} e^v$$ $$\frac{dv}{dx} = \frac{e^v}{v} \Rightarrow e^{-v} v dv = dx$$ Integrating both sides: $$e^v (x + c) + 1 + v = 0$$ $f(1) = 1 \Rightarrow x = 1, y = 1$ $$\Rightarrow c = -1 - \frac{2}{e}$$ $$e^v \left( -1 - \frac{2}{e} + x \right) + 1 + v = 0$$ $$e^{\frac{y}{x}} \left( -1 - \frac{2}{e} + x \right) + 1 + \frac{y}{x} = 0$$ $x = a, y = 0 \Rightarrow a = \frac{2}{e}$ $$ae = 2$$
Question 28
Maths · Binomial Theorem · Numerical
Remainder when $64^{32^{32}}$ is divided by 9 is equal to .
Let the set $C = \left\{ (x, y) \mid x^2 - 2^y = 2023, x, y \in \mathbb{N} \right\}$. Then $\sum_{(x,y)\in C} (x + y)$ is equal to
Answer: 46
Solution
Given the equation $x^2 - 2^y = 2023$. Solving for $x$ and $y$, we find $x = 45$ and $y = 1$. Therefore, the sum $$\sum_{(x,y)=C} (x+y) = 46.$$
Question 30
Maths · Limits and Derivatives · Numerical
Let the slope of the line $45x + 5y + 3 = 0$ be $27r_1 + \frac{9r_2}{2}$ for some $r_1$, $r_2 \in \mathbb{R}$. Then $$\lim_{x \to 3} \left( \int_{3}^{x} \frac{8t^2}{\frac{3r_2x}{2} - r_2x^2 - r_1x^3 - 3x} \, dt \right)$$ is equal to
Physics · Dual Nature of Radiation and Matter · Single correct
Two sources of light emit with a power of 200 $\mathrm{W}$. The ratio of number of photons of visible light emitted by each source having wavelengths 300 $\mathrm{nm}$ and 500 $\mathrm{nm}$ respectively, will be:
The expression for the output is given by $$Y = A \cdot \overline{B} + \overline{A} \cdot B.$$ This can be rewritten as $$= (A + \overline{A}) \cdot B.$$ Since $A + \overline{A} = 1$, we have $$Y = 1 \cdot B.$$ Therefore, the final output is $$Y = B.$$
Question 33
Physics · Mathematics in Physics · Single correct
A physical quantity $Q$ is found to depend on quantities $a, b, c$ by the relation $Q = \frac{a^4 b^3}{c^2}$. The percentage error in $a, b$ and $c$ are $3\%$, $4\%$ and $5\%$ respectively. Then, the percentage error in $Q$ is:
66$\%$
43$\%$
34$\%$
14$\%$
Answer: (c)
Solution
Given $$Q = \frac{a^4 b^3}{c^2}$$ The relative error in $Q$ is given by $$\frac{\Delta Q}{Q} = 4 \frac{\Delta a}{a} + 3 \frac{\Delta b}{b} + 2 \frac{\Delta c}{c}$$ Multiplying by 100 to find the percentage error, we have $$\frac{\Delta Q}{Q} \times 100 = 4 \left( \frac{\Delta a}{a} \times 100 \right) + 3 \left( \frac{\Delta b}{b} \times 100 \right) + 2 \left( \frac{\Delta c}{c} \times 100 \right)$$ Substituting the given percentage errors, % error in $Q = 4 \times 3\% + 3 \times 4\% + 2 \times 5\%$ $$= 12\% + 12\% + 10\%$$ $$= 34\%$$
Question 34
Physics · Alternating Current · Single correct
In an a.c. circuit, voltage and current are given by: $V = 100 \sin(100t) \, \mathrm{V}$ and $I = 100 \sin\left(100t + \frac{\pi}{3}\right) \, \mathrm{mA}$ respectively. The average power dissipated in one cycle is:
The temperature of a gas having $2.0 \times 10^{25}$ molecules per cubic meter at $1.38 \, \mathrm{atm}$ (Given, $k = 1.38 \times 10^{-23} \, \mathrm{JK^{-1}}$) is:
500 K
200 K
100 K
300 K
Answer: (a)
Solution
Given the equation $PV = nRT$. We can express $PV$ as $PV = \frac{N}{N_A} RT$. Here, $N$ is the total number of molecules. The pressure $P$ is given by $P = \frac{N}{V} kT$. Substituting the values, we have: $$1.38 \times 1.01 \times 10^5 = 2 \times 10^{25} \times 1.38 \times 10^{-23} \times T$$ Simplifying, we get: $$1.01 \times 10^5 = 2 \times 10^2 \times T$$ Solving for $T$: $$T = \frac{1.01 \times 10^3}{2} \approx 500 \, \mathrm{K}$$
Question 36
Physics · Laws of Motion · Single correct
A stone of mass 900 g is tied to a string and moved in a vertical circle of radius 1 m making 10 rpm. The tension in the string, when the stone is at the lowest point is (if $\pi^2 = 9.8$ and $g = 9.8 \, \mathrm{m/s^2}$)
The bob of a pendulum was released from a horizontal position. The length of the pendulum is 10 m. If it dissipates 10$\%$ of its initial energy against air resistance, the speed with which the bob arrives at the lowest point is : [Use, $g : 10 \, \mathrm{ms^{-2}}$]
$6\sqrt{5} \, \mathrm{ms^{-1}}$
$5\sqrt{6} \, \mathrm{ms^{-1}}$
$5\sqrt{5} \, \mathrm{ms^{-1}}$
$2\sqrt{5} \, \mathrm{ms^{-1}}$
Answer: (a)
Solution
Given $\ell = 10 \, \mathrm{m}$. Initial energy $= mg\ell$. So, $\($ $\frac{9}{10}$ mg$\ell$ = $\frac{1}{2}$ mv^2 $\)$. Therefore, $\($ $\frac{9}{10}$ $\times$ 10 $\times$ 10 = $\frac{1}{2}$ v^2 $\)$. Solving for $v^2$, we get $v^2 = 180$. Thus, $v = \sqrt{180} = 6\sqrt{5} \, \mathrm{m/s}$.
Question 38
Physics · Ray Optics and Optical Instruments · Single correct
If the distance between object and its two times magnified virtual image produced by a curved mirror is 15 cm, the focal length of the mirror must be:
15 $\mathrm{cm}$
-12 $\mathrm{cm}$
-10 $\mathrm{cm}$
$\frac{10}{3}$ $\mathrm{cm}$
Answer: (c)
Solution
Given the magnification $m = 2$, we have: $$m = \frac{-v}{u}$$ Substituting $v = 15 - u$, we get: $$2 = \frac{-(15 - u)}{-u}$$ Simplifying, we find: $$2u = 15 - u$$ $$3u = 15 \Rightarrow u = 5 \, \mathrm{cm}$$ Now, substituting back to find $v$: $$v = 15 - u = 15 - 5 = 10 \, \mathrm{cm}$$ Using the lens formula: $$\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$$ Substitute the values: $$\frac{1}{f} = \frac{1}{10} + \frac{1}{(-5)} = \frac{1 - 2}{10} = \frac{-1}{10}$$ Thus, the focal length is: $$f = -10 \, \mathrm{cm}$$
Question 39
Physics · Moving Charges and Magnetism · Single correct
Two particles X and Y having equal charges are being accelerated through the same potential difference. Thereafter they enter normally in a region of uniform magnetic field and describes circular paths of radii $R_1$ and $R_2$ respectively. The mass ratio of X and Y is:
$\left(\frac{R_2}{R_1}\right)^2$
$\left(\frac{R_1}{R_2}\right)^2$
$\frac{R_1}{R_2}$
$\frac{R_2}{R_1}$
Answer: (b)
Solution
Given $$R = \frac{mv}{qB} = \frac{p}{qB} = \frac{\sqrt{2\, m (\mathrm{KE})}}{qB} = \frac{\sqrt{2mqV}}{qB}$$ We have $$R \propto \sqrt{m}$$ And $$m \propto R^2$$ Thus, $$\frac{m_1}{m_2} = \left(\frac{R_1}{R_2}\right)^2$$
Question 40
Physics · Wave Optics · Single correct
In Young's double slit experiment, light from two identical sources are superimposing on a screen. The path difference between the two lights reaching at a point on the screen is $\frac{7\lambda}{4}$. The ratio of intensity of fringe at this point with respect to the maximum intensity of the fringe is :
A bob of mass ' $m$ ' is suspended by a light string of length ' $L$ '. It is imparted a minimum horizontal velocity at the lowest point A such that it just completes half circle reaching the top most position B. The ratio of kinetic energies $\frac{(\mathrm{K.E.})_A}{(\mathrm{K.E.})_B}$ is:
3 : 2
5 : 1
2 : 5
1 : 5
Answer: (b)
Solution
Apply energy conservation between A and B $$\frac{1}{2} m V_L^2 = \frac{1}{2} m V_H^2 + mg(2L)$$ Therefore, $V_L = \sqrt{5gL}$ So, $V_H = \sqrt{gL}$ $$\frac{(\mathrm{K.E})_A}{(\mathrm{K.E})_B} = \frac{\frac{1}{2} m (\sqrt{5gL})^2}{\frac{1}{2} m (\sqrt{gL})^2} = \frac{5}{1}$$
Question 43
Physics · Mechanical Properties of Solids · Single correct
A wire of length $L$ and radius $r$ is clamped at one end. If its other end is pulled by a force $F$, its length increases by $l$. If the radius of the wire and the applied force both are reduced to half of their original values keeping original length constant, the increase in length will become.
3 times
3/2 times
4 times
2 times
Answer: (d)
Solution
Given $$Y = \frac{stress}{strain}$$ $$Y = \frac{\frac{F}{\ell/2}}{\frac{\ell}{L}}$$ $$F = Y \pi r^2 \times \frac{\ell}{L} \cdots (i)$$ $$Y = \frac{\frac{F r/2}{\Delta \ell/2}}{L}$$ $$F = Y \frac{\Delta \ell}{L} \times 2 \times \frac{\pi r^2}{4}$$ From (i) $$Y \pi r^2 \frac{\ell}{L} = Y \frac{\Delta \ell}{L} \frac{\pi r^2}{2}$$ $$\Delta \ell = 2 \ell$$
Question 44
Physics · Gravitation · Single correct
A planet takes 200 days to complete one revolution around the Sun. If the distance of the planet from Sun is reduced to one fourth of the original distance, how many days will it take to complete one revolution?
25
50
100
20
Answer: (a)
Solution
Given $T^2 \propto r^3$. Therefore, $\($ $\frac{T_1^2}{r_1^3}$ = $\frac{T_2^2}{r_2^3}$ $\)$. Substituting the given values, $\($ $\frac{(200)^2}{r^3}$ = $\frac{T_2^2}{\left(\frac{r}{4}\right)^3}$ $\)$. Simplifying, $\($ $\frac{200 \times 200}{4 \times 4 \times 4}$ = T_2^2 $\)$. Solving for $T_2$, we get $\($ T_2 = $\frac{200}{4 \times 2}$ $\)$. Therefore, $T_2 = 25$ days.
Question 45
Physics · Electromagnetic Waves · Single correct
A plane electromagnetic wave of frequency 35 $\mathrm{MHz}$ travels in free space along the X-direction. At a particular point (in space and time) $\vec{E} = 9.6\hat{j} \, \mathrm{V/m}$. The value of magnetic field at this point is :
$3.2$ $\times$ $10^{-8}$$\hat{k}$ $\mathrm{T}$
$3.2$ $\times$ $10^{-8}$ $\hat{i}$ $\mathrm{T}$
$9.6$ $\hat{j}$ $\mathrm{T}$
$9.6$ $\times$ $10^{-8}$ $\hat{k}$ $\mathrm{T}$
Answer: (a)
Solution
Given $\($ $\frac{E}{B}$ = C $\)$ and $\($ $\frac{E}{B}$ = 3 $\times$ 10^8 $\)$. Therefore, $\($ B = $\frac{E}{3 \times 10^8}$ = $\frac{9.6}{3 \times 10^8}$ $\)$. Thus, $\($ B = 3.2 $\times$ 10^{-8} $\mathrm{T}$ $\)$. The direction of $\($ $\mathbf{\hat{B}}$ = $\mathbf{\hat{v}}$ $\times$ $\mathbf{\hat{E}}$ $\)$ is $\($ $\mathbf{\hat{i}}$ $\times$ $\mathbf{\hat{j}}$ = $\mathbf{\hat{k}}$ $\)$. So, $\($ $\mathbf{B}$ = 3.2 $\times$ 10^{-8} $\mathbf{\hat{k}}$ $\mathrm{T}$ $\)$.
Question 46
Physics · Current Electricity · Single correct
In the given circuit, the current in resistance $R_3$ is:
$1\,\mathrm{A}$
$1.5\,\mathrm{A}$
$2\,\mathrm{A}$
$2.5\,\mathrm{A}$
Answer: (a)
Solution
The equivalent resistance is given by $R_{eq} = 2\,\Omega + 2\,\Omega + 1\,\Omega = 5\,\Omega$. The current $i$ is calculated as $i = \frac{V}{R_{eq}} = \frac{10}{5} = 2\,A$. Current in resistance $R_3$ is calculated as follows: $$R_3 = 2 \times \left( \frac{4}{4 + 4} \right)$$ $$= 2 \times \frac{4}{8}$$ $$= 1\,A$$
Question 47
Physics · Motion in a Straight Line · Single correct
A particle is moving in a straight line. The variation of position ' $x$ ' as a function of time ' $t$ ' is given as $$x = (t^3 - 6t^2 + 20t + 15) \, \mathrm{m}.$$ The velocity of the body when its acceleration becomes zero is :
4 m/s
8 m/s
10 m/s
6 m/s
Answer: (b)
Solution
Given $x = t^3 - 6t^2 + 20t + 15$. Differentiate with respect to $t$: $$\frac{dx}{dt} = v = 3t^2 - 12t + 20$$ Differentiate again to find acceleration: $$\frac{dv}{dt} = a = 6t - 12$$ When $a = 0$, solve for $t$: $$6t - 12 = 0; \ t = 2 sec$$ At $t = 2 sec$, calculate $v$: $$v = 3(2)^2 - 12(2) + 20$$ $$v = 8 \, \mathrm{m/s}$$
Question 48
Physics · Kinetic Theory · Single correct
N moles of a polyatomic gas $(f = 6)$ must be mixed with two moles of a monoatomic gas so that the mixture behaves as a diatomic gas. The value of $N$ is:
6
3
4
2
Answer: (c)
Solution
Given the equation for $f_{eq}$: $$f_{eq} = \frac{n_1 f_1 + n_2 f_2}{n_1 + n_2}$$ For diatomic gas, $f_{eq} = 5$. $$5 = \frac{(N)(6) + (2)(3)}{N + 2}$$ Simplifying, we have: $$5N + 10 = 6N + 6$$ Solving for $N$: $$N = 4$$
Question 49
Physics · Atoms · Single correct
Given below are two statements:\ Statement I : Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford's model.\ Statement II : An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford's model.\ In the light of the above statements, choose the most appropriate from the options given below.
Both statement I and statement II are false
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
Answer: (c)
Solution
According to Rutherford atomic model, most of mass of atom and all its positive charge is concentrated in tiny nucleus and electron revolve around it. According to Thomson atomic model, atom is spherical cloud of positive charge with electron embedded in it. Hence, Statement I is true but statement II false.
Question 50
Physics · Electric Charges and Fields · Single correct
An electric field is given by $(6\hat{i} + 5\hat{j} + 3\hat{k}) \, \mathrm{N/C}$. The electric flux through a surface area $30\hat{i} \, \mathrm{m^2}$ lying in YZ-plane (in SI unit) is :
90
150
180
60
Answer: (c)
Solution
Given $\vec{E} = 6\hat{i} + 5\hat{j} + 3\hat{k}$ and $\vec{A} = 30\hat{i}$. The flux $\phi$ is given by the dot product $\vec{E} \cdot \vec{A}$. Therefore, $$\phi = (6\hat{i} + 5\hat{j} + 3\hat{k}) \cdot (30\hat{i})$$ $$\phi = 6 \times 30 = 180$$
Question 51
Physics · Mechanical Properties of Solids · Numerical
Two metallic wires P and Q have same volume and are made up of same material. If their area of cross sections are in the ratio 4 : 1 and force $F_1$ is applied to P, an extension of $\Delta l$ is produced. The force which is required to produce same extension in Q is $F_2$. The value of $\frac{F_1}{F_2}$ is
Answer: 16
Solution
Given $$Y = \frac{Stress}{Strain} = \frac{F/A}{\Delta \ell / \ell} = \frac{F \ell}{A \Delta \ell}$$ $$\Delta \ell = \frac{F \ell}{A Y}$$ $$V = A \ell \Rightarrow \ell = \frac{V}{A}$$ $$\Delta \ell = \frac{F V}{A^2 Y}$$ $Y$ and $V$ are the same for both the wires. $$\Delta \ell \propto \frac{F}{A^2}$$ $$\frac{\Delta \ell_1}{\Delta \ell_2} = \frac{F_1}{A_1^2} \times \frac{A_2^2}{F_2}$$ $$\Delta \ell_1 = \Delta \ell_2$$ $$F_1 A_2^2 = F_2 A_1^2$$ $$\frac{F_1}{F_2} = \frac{A_1^2}{A_2^2} = \left( \frac{4}{1} \right)^2 = 16$$
Question 52
Physics · Electromagnetic Induction · Numerical
A horizontal straight wire 5 m long extending from east to west falling freely at right angle to horizontal component of earth's magnetic field $0.60 \times 10^{-4} \, \mathrm{Wb} \, \mathrm{m}^{-2}$. The instantaneous value of emf induced in the wire when its velocity is $10 \, \mathrm{ms}^{-1}$ is _____ $\times 10^{-3} \, \mathrm{V}$
Hydrogen atom is bombarded with electrons accelerated through a potential different of $V$, which causes excitation of hydrogen atoms. If the experiment is being formed at $T = 0 \, \mathrm{K}$. The minimum potential difference needed to observe any Balmer series lines in the emission spectra will be $\frac{\alpha}{10} \, V$, where $\alpha$ =
Answer: 121
Solution
For minimum potential difference electron has to make transition from $n = 3$ to $n = 2$ state but first electron has to reach to $n = 3$ state from ground state. So, energy of bombarding electron should be equal to energy difference of $n = 3$ and $n = 1$ state. $$\Delta E = 13.6 \left[ 1 - \frac{1}{3^2} \right] e = \mathrm{eV}$$ $$\frac{13.6 \times 8}{9} = V$$ $$V = 12.09 \, \mathrm{V} \approx 12.1 \, \mathrm{V}$$ So, $\alpha = 121$
Question 54
Physics · Moving Charges and Magnetism · Numerical
A charge of $4.0\,\mu\mathrm{C}$ is moving with a velocity of $4.0 \times 10^6\,\mathrm{m\,s}^{-1}$ along the positive $y$-axis under a magnetic field $\mathbf{B}$ of strength $(2\hat{k})\,\mathrm{T}$. The force acting on the charge is $x\hat{i}\,\mathrm{N}$. The value of $x$ is
Answer: 32
Solution
Given $q = 4 \, \mu \mathrm{C}$, $\vec{v} = 4 \times 10^6 \hat{\jmath} \, \mathrm{m/s}$ and $\vec{B} = 2 \hat{k} \, \mathrm{T}$. The force $\vec{F}$ is given by $q(\vec{v} \times \vec{B})$. $$\vec{F} = 4 \times 10^{-6} \left( 4 \times 10^6 \hat{\jmath} \times 2 \hat{k} \right)$$ $$= 4 \times 10^{-6} \times 8 \times 10^6 \hat{\imath}$$ $$\vec{F} = 32 \hat{\imath} \, \mathrm{N}$$ Therefore, $x = 32$.
Question 55
Physics · Oscillations · Fill in the blank
A simple harmonic oscillator has an amplitude $A$ and time period $6\pi$ seconds. Assuming the oscillation starts from its mean position, the time required by it to travel from $x = A$ to $x = \frac{\sqrt{3}}{2}A$ will be $\frac{\pi}{x}$ s, where x = _____
Answer: 2
Solution
From phasor diagram particle has to move from P to Q in a circle of radius equal to amplitude of SHM. $$\cos \phi = \frac{\sqrt{3} A}{2 A} = \frac{\sqrt{3}}{2}$$ $$\phi = \frac{\pi}{6}$$ Now, $$\frac{\pi}{6} = \omega t$$ $$\frac{\pi}{6} = \frac{2\pi}{T} t$$ $$\frac{\pi}{6} = \frac{2\pi}{6\pi} t$$ $$t = \frac{\pi}{2}$$ So, $$x = 2$$
Question 56
Physics · Alternating Current · Numerical
In the given figure, the charge stored in $6\mu F$ capacitor, when points A and B are joined by a connecting wire is ______ $\mu C$.
Answer: 36
Solution
At steady state, the capacitor behaves as an open circuit and current flows in the circuit as shown in the diagram. $$R_{eq} = 9 \, \Omega$$ $$i = \frac{9 \, V}{9 \, \Omega} = 1 \, A$$ $$\Delta V_{6\Omega} = 1 \times 6 = 6 \, V$$ $$V_A = 3 \, V$$ So, the potential difference across $6 \, \mu F$ is $6 \, V$. Hence $$Q = C \Delta V$$ $$= 6 \times 6 \times 10^{-6} \, C$$ $$= 36 \, \mu C$$
Question 57
Physics · Wave Optics · Numerical
In a single slit diffraction pattern, a light of wavelength $6000\,\mathrm{\AA}$ is used. The distance between the first and third minima in the diffraction pattern is found to be $3\,\mathrm{mm}$ when the screen in placed $50\,\mathrm{cm}$ away from slits. The width of the slit is _____ $\times 10^{-4}\,\mathrm{m}$.
Answer: 2
Solution
For $n^{th}$ minima $$b \sin \theta = n \lambda$$ ($\lambda$ is small so $\sin \theta$ is small, hence $\sin \theta \simeq \tan \theta$) $$b \tan \theta = n \lambda$$ $$\frac{b}{D} y = n \lambda$$ $$\Rightarrow \; y_n = \frac{n \lambda D}{b} \; (Position of $n^{th}$ minima)$$ $B \rightarrow 1^{st}$ minima, $A \rightarrow 3^{rd}$ minima $$y_3 = \frac{3 \lambda D}{b}, \; y_1 = \frac{\lambda D}{b}$$ $$\Delta y = y_3 - y_1 = \frac{2 \lambda D}{b}$$ $$3 \times 10^{-3} = \frac{2 \times 6000 \times 10^{-10} \times 0.5}{b}$$ $$b = \frac{2 \times 6000 \times 10^{-10} \times 0.5}{3 \times 10^{-3}}$$ $$b = 2 \times 10^{-4} \, \mathrm{m}$$ $$x = 2$$
Question 58
Physics · Current Electricity · Numerical
In the given circuit, the current flowing through the resistance $20 \, \Omega$ is $0.3 \, \mathrm{A}$, while the ammeter reads $0.9 \, \mathrm{A}$. The value of $R_1$ is _____ $\Omega$.
A particle is moving in a circle of radius 50 $\mathrm{\ cm}$ in such a way that at any instant the normal and tangential components of its acceleration are equal. If its speed at t = 0 is 4 $\mathrm{\ m/s}$, the time taken to complete the first revolution will be $\frac{1}{\alpha}$ [ 1 - $e^{-2\pi}$] $\mathrm{\ s}$, where $\alpha$ = .
Answer: 8
Solution
Given $|\vec{a}_c| = |\vec{a}_t|$. $$\frac{v^2}{r} = \frac{dv}{dt}$$ This implies $$\int_4^v \frac{dv}{v^2} = \int_0^t \frac{dt}{r}$$ Therefore, $$\left[ -\frac{1}{v} \right]_4^v = \frac{t}{r}$$ This gives $$-\frac{1}{v} + \frac{1}{4} = 2t$$ Thus, $$v = \frac{4}{1 - 8t} = \frac{ds}{dt}$$ Integrating, $$4 \int_0^t \frac{dt}{1 - 8t} = \int_0^s ds$$ Given $r = 0.5 \, \mathrm{m}$ and $s = 2\pi r = \pi$, we have $$4 \times \left[ \ln(1 - 8t) \right]_0^t = \pi$$ This simplifies to $$\frac{\ln(1 - 8t)}{-8} = -2\pi$$ Therefore, $$1 - 8t = e^{-2\pi}$$ Solving for $t$, $$t = \left(1 - e^{-2\pi}\right) \frac{1}{8} s$$ So, $\alpha = 8$
Question 60
Physics · System of Particles and Rotational Motion · Numerical
A body of mass 5 kg moving with a uniform speed $3\sqrt{2} \, \mathrm{ms}^{-1}$ in $X - Y$ plane along the line $y = x + 4$. The angular momentum of the particle about the origin will be _____ $\mathrm{kgm}^2 \mathrm{s}^{-1}$.
Answer: 60
Solution
Given the equation of the line: $$y - x - 4 = 0$$ $d_1$ is the perpendicular distance of the given line from the origin. $$d_1 = \left| \frac{-4}{\sqrt{1^2 + 1^2}} \right| \Rightarrow 2\sqrt{2} \, \mathrm{m}$$ So, $$|\vec{L}| = m v d_1 = 5 \times 3\sqrt{2} \times 2\sqrt{2} \, \mathrm{kg \, m^2/s}$$ $$= 60 \, \mathrm{kg \, m^2/s}$$
Chemistry
Question 61
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
The ascending acidity order of the following H atoms is
C < D < B < A
A < B < C < D
A < B < D < C
D < C < B < A
Answer: (a)
Solution
The stability of the conjugate base is proportional to acidic strength. The order is $\mathrm{C} < \mathrm{D} < \mathrm{B} < \mathrm{A}$.
Question 62
Chemistry · Biomolecules · Single correct
Match List I with List II \begin{tabular}{|l|l|} \hline \textbf{List I (Bio Polymer)} & \textbf{List II (Monomer)} \\ \hline A. Starch & I. nucleotide \\ \hline B. Cellulose & II. $\alpha$-glucose \\ \hline C. Nucleic acid & III. $\beta$-glucose \\ \hline D. Protein & IV. $\alpha$-amino acid \\ \hline \end{tabular} Choose the correct answer from the options given below :-
A-II, B-I, C-III, D-IV
A-IV, B-II, C-I, D-III
A-I, B-III, C-IV, D-II
A-II, B-III, C-I, D-IV
Answer: (d)
Solution
A-II, B-III, C-I, D-IV Fact based.
Question 63
Chemistry · Analytical Chemistry · Single correct
Match List I with List II Choose the correct answer from the options given below :-
The reaction involves the addition of HI to the alkene. According to Markovnikov's rule, the iodine (I) will add to the more substituted carbon atom, resulting in the formation of the product shown.
Question 65
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
According to IUPAC system, the compound is named as
Cyclohex-1-en-2-ol
1-Hydroxyhex-2-ene
Cyclohex-1-en-3-ol
Cyclohex-2-en-1-ol
Answer: (d)
Solution
Cyclohex-2-en-1-ol
Question 66
Chemistry · Co-ordination Compounds · Single correct
The correct IUPAC name of $\mathrm{K_2MnO_4}$ is
Potassium tetraoxopermanganate (VI)
Potassium tetraoxidomanganate (VI)
Dipotassium tetraoxidomanganate (VII)
Potassium tetraoxidomanganese (VI)
Answer: (b)
Solution
Given $\mathrm{K_2MnO_4}$. $2 + x - 8 = 0$ Therefore, $x = +6$. The oxidation state of Mn is $+6$. IUPAC Name = Potassium tetraoxidomanganate(VI)
Question 67
Chemistry · Analytical Chemistry · Single correct
A reagent which gives brilliant red precipitate with Nickel ions in basic medium is
sodium nitroprusside
neutral FeCl_3
meta-dinitrobenzene
dimethyl glyoxime
Answer: (d)
Solution
The reaction is given by: $$\mathrm{Ni^{2+} + 2dmg^- \rightarrow [Ni(dmg)_2]}$$ This results in a rosy red or bright red precipitate.
Question 68
Chemistry · Alcohols, Phenols and Ethers · Single correct
Phenol treated with chloroform in presence of sodium hydroxide, which further hydrolysed in presence of an acid results
Salicyclic acid
Benzene-1,2-diol
Benzene-1, 3-diol
2-Hydroxybenzaldehyde
Answer: (d)
Solution
It is Reimer Tiemann Reaction
Question 69
Chemistry · Structure of Atom · Single correct
Match List I with List II \begin{tabular}{|l|l|} \hline \textbf{List-I} (Spectral Series for Hydrogen) & \textbf{List-II} ((Spectral Region/Higher Energy State) \\ \hline (A) Lyman & I. Infrared region \\ \hline (B) Balmer & II. UV region \\ \hline (C) Paschen & III. Infrared region \\ \hline (D) Pfund & IV. Visible region\\ \hline \end{tabular}
A-II, B-III, C-I, D-IV
A-I, B-III, C-II, D-IV
A-II, B-IV, C-III, D-I
A-I, B-II, C-III, D-IV
Answer: (c)
Solution
A - II, B - IV, C - III, D - I Fact based.
Question 70
Chemistry · Analytical Chemistry · Single correct
On passing a gas, 'X', through Nessler's reagent, a brown precipitate is obtained. The gas 'X' is
$\mathrm{H_2S}$
$\mathrm{CO_2}$
$\mathrm{NH_3}$
$\mathrm{Cl_2}$
Answer: (c)
Solution
Nessler's Reagent Reaction: $$2 \, \mathrm{K_2HgI_4} + \mathrm{NH_3} + 3\mathrm{KOH} \rightarrow \mathrm{HgO.Hg(NH_2)I} + 7\mathrm{KI} + 2\mathrm{H_2O}$$ (Nessler’s Reagent) (iodine of Millon’s base Brown precipitate)
Question 71
Chemistry · Amines · Single correct
The product A formed in the following reaction is:
Answer: (c)
Solution
The reaction involves the conversion of aniline to chlorobenzene. First, aniline ($\mathrm{C_6H_5NH_2}$) is treated with $\mathrm{NaNO_2}$ and $\mathrm{HCl}$ at $0^\circ \mathrm{C}$ to form a diazonium salt ($\mathrm{C_6H_5N_2^+Cl^-}$). This is followed by a Sandmeyer reaction using $\mathrm{Cu_2Cl_2}$ to replace the diazonium group with a chlorine atom, resulting in chlorobenzene ($\mathrm{C_6H_5Cl}$).
Question 72
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
Identify the reagents used for the following conversion
A = $\mathrm{LiAlH_4}$, B = $\mathrm{NaOH_{(aq)}}$, C = $\mathrm{NH_2 - NH_2/KOH}$, ethylene glycol
A = $\mathrm{LiAlH_4}$, B = $\mathrm{NaOH_{(alc)}}$, C = $\mathrm{Zn/HCl}$
A = $\mathrm{DIBAL-H}$, B = $\mathrm{NaOH_{(aq)}}$, C = $\mathrm{NH_2 - NH_2/KOH}$, ethylene glycol
A = $\mathrm{DIBAL-H}$, B = $\mathrm{NaOH_{(alc)}}$, C = $\mathrm{Zn/HCl}$
Answer: (d)
Solution
The reaction sequence involves three main steps. First, the ester group is selectively reduced to an aldehyde using DIBAL-H. This is followed by an intramolecular aldol condensation facilitated by alcoholic NaOH, leading to the formation of a cyclic compound with an aldehyde group. Finally, Clemmensen reduction using Zn/HCl removes the carbonyl group, resulting in the formation of the final product.
Question 73
Chemistry · The d-and f-Block Elements · Single correct
Which of the following acts as a strong reducing agent? (Atomic number : Ce = 58, Eu = 63, Gd = 64, Lu = 71)
$\mathrm{Lu}^{3+}$
$\mathrm{Gd}^{3+}$
$\mathrm{Eu}^{2+}$
$\mathrm{Ce}^{4+}$
Answer: (c)
Solution
For $\mathrm{Eu}^{+2}$, the electron configuration is $[\mathrm{Xe}]4f^7 6s^0$. When $\mathrm{Eu}^{+3}$ is formed, it loses one electron: $[\mathrm{Xe}]4f^7 6s^0 \rightarrow \mathrm{Eu}^{+3} + 1e^-$. The resulting configuration is $[\mathrm{Xe}]4f^6 6s^0$.
Question 74
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Chromatographic technique/s based on the principle of differential adsorption is/are\ A. Column chromatography\ B. Thin layer chromatography\ C. Paper chromatography\ Choose the most appropriate answer from the options given below:
B only
A only
A $\&$ B only
C only
Answer: (c)
Question 75
Chemistry · The d-and f-Block Elements · Single correct
Which of the following statements are correct about Zn, Cd and Hg? A. They exhibit high enthalpy of atomization as the d-subshell is full. B. Zn and Cd do not show variable oxidation state while Hg shows +I and +II. C. Compounds of Zn, Cd and Hg are paramagnetic in nature. D. Zn, Cd and Hg are called soft metals. Choose the most appropriate from the options given below:
B, D only
B, C only
A, D only
C, D only
Answer: (a)
Solution
Q11 (A) $\mathrm{Zn}$, $\mathrm{Cd}$, $\mathrm{Hg}$ exhibit lowest enthalpy of atomization in respective transition series. (C) Compounds of $\mathrm{Zn}$, $\mathrm{Cd}$ and $\mathrm{Hg}$ are diamagnetic in nature.
Question 76
Chemistry · Classification of Elements and Periodicity in Properties · Single correct
The element having the highest first ionization enthalpy is
Si
Al
N
C
Answer: (c)
Solution
Al < Si < C < N; IE_1 order.
Question 77
Chemistry · Haloalkanes and Haloarenes · Single correct
Alkyl halide is converted into alkyl isocyanide by reaction with
NaCN
NH_4CN
KCN
AgCN
Answer: (d)
Solution
Covalent character of $\mathrm{AgCN}$.
Question 78
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Which one of the following will show geometrical isomerism?
Answer: (c)
Solution
Due to unsymmetrical.
Question 79
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct
Given below are two statements:\ Statement I: Fluorine has most negative electron gain enthalpy in its group.\ Statement II: Oxygen has least negative electron gain enthalpy in its group.\ In the light of the above statements, choose the most appropriate from the options given below.
Both Statement I and Statement II are true
Statement I is true but Statement II is false
Both Statement I and Statement II are false
Statement I is false but Statement II is true
Answer: (d)
Solution
Statement-1 is false because chlorine has most negative electron gain enthalpy in its group.
Question 80
Chemistry · Classification of Elements and Periodicity in Properties · Single correct
Anomalous behaviour of oxygen is due to its
Large size and high electronegativity
Small size and low electronegativity
Small size and high electronegativity
Large size and low electronegativity
Answer: (c)
Solution
Fact Based.
Question 81
Chemistry · Chemical Bonding and Molecular Structure · Numerical
The total number of anti bonding molecular orbitals, formed from 2s and 2p atomic orbitals in a diatomic molecule is
Answer: 4
Solution
Antibonding molecular orbital from $2s = 1$ Antibonding molecular orbital from $2p = 3$ Total $= 4$
Question 82
Chemistry · Analytical Chemistry · Numerical
The oxidation number of iron in the compound formed during brown ring test for $\mathrm{NO}_3^-$ ion is
Answer: 1
Solution
The complex is $[\mathrm{Fe(H_2O)_5(NO)]^{2+}}$. The oxidation number of $\mathrm{Fe}$ is $+1$.
Question 83
Chemistry · Equilibrium · Numerical
The following concentrations were observed at 500 K for the formation of $NH_3$ from $N_2$ and $H_2$. At equilibrium: $[N_2] = 2 \times 10^{-2} \, \mathrm{M}$, $[H_2] = 3 \times 10^{-2} \, \mathrm{M}$ and $[NH_3] = 1.5 \times 10^{-2} \, \mathrm{M}$. Equilibrium constant for the reaction is
Answer: 417
Solution
Given the equilibrium constant expression: $$K_C = \frac{[\mathrm{NH_3}]^2}{[\mathrm{N_2}][\mathrm{H_2}]^3}$$ Substitute the given concentrations: $$K_C = \frac{(1.5 \times 10^{-2})^2}{(2 \times 10^{-2}) \times (3 \times 10^{-2})^3}$$ Calculate the value: $$K_C = 417$$
Question 84
Chemistry · Solutions · Numerical
Molality of 0.8M $\mathrm{H}_2\mathrm{SO}_4$ solution (density $1.06 \, \mathrm{g} \, \mathrm{cm}^{-3}$) is _______ $\times 10^{-3}$ m.
Answer: 815
Solution
Given the formula for molality: $$m = \frac{M \times 1000}{d_{sol} \times 1000 - M \times Molar mass_{solute}}$$ The calculated molality is $815 \times 10^{-3} \, m$.
Question 85
Chemistry · Some Basic Concepts of Chemistry · Numerical
If 50 $\mathrm{mL}$ of 0.5 $\mathrm{M}$ oxalic acid is required to neutralise 25 $\mathrm{mL}$ of NaOH solution, the amount of NaOH in 50 $\mathrm{mL}$ of given NaOH solution is ______$\mathrm{g}$.
Answer: 4
Solution
Equivalent of Oxalic acid = Equivalents of NaOH $$50 \times 0.5 \times 2 = 25 \times M \times 1$$ $$M_{NaOH} = 2\, M$$ $$W_{NaOH} in 50\, ml$ $ = 2 \times 50 \times 40 \times 10^{-3}\, g = 4\, g$$
Question 86
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Numerical
The total number of 'Sigma' and Pi bonds in 2-formylhex-4-enoic acid is
Answer: 22
Solution
The molecule shown has a total of 22 bonds.
Question 87
Chemistry · Chemical Kinetics and Nuclear Chemistry · Numerical
The half-life of radioisotopic bromine - 82 is 36 hours. The fraction which remains after one day is $\underline{\hspace{0.6cm}}\times 10^{-2}$. (Given antilog 0.2006 = 1.587)
Answer: 63
Solution
Half life of bromine-82 = 36 hours $$t_{1/2} = \frac{0.693}{K}$$ $$K = \frac{0.693}{36} = 0.01925 \, \mathrm{hr}^{-1}$$ First order reaction kinetic equation $$t = \frac{2.303}{K} \log \frac{a}{a-x}$$ $$\log \frac{a}{a-x} = \frac{t \times K}{2.303} (t = 1 \, \mathrm{day} = 24 \, \mathrm{hr})$$ $$\log \frac{a}{a-x} = \frac{24 \, \mathrm{hr} \times 0.01925 \, \mathrm{hr}^{-1}}{2.303}$$ $$\log \frac{a}{a-x} = 0.2006$$ $$\frac{a}{a-x} = anti log(0.2006)$$ $$\frac{a}{a-x} = 1.587$$ If $a = 1$ $$\frac{1}{1-x} = 1.587 \Rightarrow 1-x = 0.6301 = Fraction remain after one day$$
Question 88
Chemistry · Thermodynamics · Fill in the blank
Standard enthalpy of vapourisation for $\mathrm{CCl_4}$ is $30.5\,\mathrm{kJ\,mol^{-1}}$. Heat required for vapourisation of $284\,\mathrm{g}$ of $\mathrm{CCl_4}$ at constant temperature is $\underline{\hspace{1cm}}\,\mathrm{kJ}$. (Given molar mass in $\mathrm{g\,mol^{-1}}$; $\mathrm{C}=12$, $\mathrm{Cl}=35.5$)
Answer: 56
Solution
Given $\Delta H^0_{vap} \ \mathrm{CCl_4} = 30.5 \, \mathrm{kJ/mol}$. Mass of $\mathrm{CCl_4} = 284 \, \mathrm{gm}$. Molar mass of $\mathrm{CCl_4} = 154 \, \mathrm{g/mol}$. Moles of $\mathrm{CCl_4} = \frac{284}{154} = 1.844 \, \mathrm{mol}$. $\Delta H^0_{vap}$ for 1 mole $= 30.5 \, \mathrm{kJ/mol}$. $\Delta H^0_{vap}$ for 1.844 mol $= 30.5 \times 1.844 = 56.242 \, \mathrm{kJ}$.
Question 89
Chemistry · Electrochemistry · Numerical
A constant current was passed through a solution of $\mathrm{AuCl}_4^-$ ion between gold electrodes. After a period of 10.0 minutes, the increase in mass of cathode was 1.314 g. The total charge passed through the solution is ____ $\times$ $10^{-2}$ $\mathrm{F}$. (Given atomic mass of $\mathrm{Au} = 197$)
Answer: 2
Solution
Given $\frac{W}{E}=\frac{\text{charge}}{1\,\mathrm{F}}$. $1.314\times\frac{197}{3}=\frac{Q}{1\,\mathrm{F}}$ $Q=2\times10^{-2}\,\mathrm{F}$
Question 90
Chemistry · Chemical Bonding and Molecular Structure · Numerical
The total number of molecules with zero dipole moment among $\mathrm{CH}_4$, $\mathrm{BF}_3$, $\mathrm{H}_2\mathrm{O}$, $\mathrm{HF}$, $\mathrm{NH}_3$, $\mathrm{CO}_2$ and $\mathrm{SO}_2$ is
Answer: 3
Solution
Molecules with zero dipole moment are $\mathrm{CO_2}$, $\mathrm{CH_4}$, $\mathrm{BF_3}$.