JEE Main 5 April 2026 Shift 1 question paper with solutions

JEE Main 5 April 2026 Shift 1: 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 · Complex Numbers and Quadratic Equations · Single correct

Let $a, b \in \mathbb{C}$. Let $\alpha, \beta$ be the roots of the equation $x^2 + ax + b = 0$. If $\beta - \alpha = \sqrt{11}$ and $\beta^2 - \alpha^2 = 3i\sqrt{11}$, then $(\beta^3 - \alpha^3)^2$ is equal to:

  1. 160
  2. 176
  3. 194
  4. 187

Answer: (b)

Solution

Given $\beta - \alpha = \sqrt{11} \ldots$ (1) and $\beta^2 - \alpha^2 = 3i \sqrt{11}$ $$\Rightarrow (\beta + \alpha)(\beta - \alpha) = 3i \sqrt{11}$$ $$\Rightarrow \beta + \alpha = 3i \ldots (2)$$ From (1) and (2) $$\beta = \frac{\sqrt{11} + 3i}{2}, \alpha = \frac{3i - \sqrt{11}}{2}$$ $$\Rightarrow \alpha \beta = \frac{-9 - 11}{4} \Rightarrow \alpha \beta = -5$$ Now $\left(\beta^3 - \alpha^3\right)^2 = (\beta - \alpha)^2(\beta^2 + \alpha^2 + \alpha \beta)^2$ $$= (\beta - \alpha)^2((\beta + \alpha)^2 - \alpha \beta)^2$$ $$= (11)(-9 + 5)^2 = 176$$

Question 2

Maths · Sequences and Series · Single correct

Let the sum of the first n terms of an A.P. be $3n^2 + 5n$. Then the sum of squares of the first 10 terms of the A.P. is:

  1. 10220
  2. 12860
  3. 15220
  4. 19780

Answer: (c)

Solution

Given $S_n = 3n^2 + 5n$. $T_n = S_n - S_{n-1}$. Therefore, $T_n = (3n^2 + 5n) - (3(n-1)^2) + 5(n-1))$. This simplifies to $T_n = 6n + 2$. The sum $\sum_{n=1}^{10} T_n^2 = \sum_{n=1}^{10} (6n + 2)^2$. This equals $36 \sum_{n=1}^{10} n^2 + 24 \sum_{n=1}^{10} n + \sum_{n=1}^{10} 4$. The final result is $15220$.

Question 3

Maths · Determinants · Single correct

Let $A$ be a $3\times3$ matrix such that $$A^T\begin{bmatrix}1\\0\\1\end{bmatrix}=\begin{bmatrix}5\\2\\2\end{bmatrix},\quad A^T\begin{bmatrix}0\\0\\1\end{bmatrix}=\begin{bmatrix}3\\1\\1\end{bmatrix},\quad A\begin{bmatrix}1\\0\\1\end{bmatrix}=\begin{bmatrix}3\\4\\4\end{bmatrix}\ \text{and}$$ $$A\begin{bmatrix}0\\0\\1\end{bmatrix}=\begin{bmatrix}1\\3\\1\end{bmatrix}$$ If $\det(A)=1$, then $\det(\operatorname{adj}(A^2+A))$ is equal to:

  1. 16
  2. 25
  3. 49
  4. 64

Answer: (d)

Solution

Let $A = \begin{pmatrix} \alpha_1 & \alpha_2 & \alpha_3 \\ \beta_1 & \beta_2 & \beta_3 \\ \gamma_1 & \gamma_2 & \gamma_3 \end{pmatrix}$. Now $A = \begin{pmatrix} \alpha_1 & \beta_1 & \gamma_1 \\ \alpha_2 & \beta_2 & \gamma_2 \\ \alpha_3 & \beta_3 & \gamma_3 \end{pmatrix} \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} = \begin{pmatrix} 3 \\ 1 \\ 1 \end{pmatrix}$. $$\Rightarrow \begin{pmatrix} \gamma_1 \\ \gamma_2 \\ \gamma_3 \end{pmatrix} = \begin{pmatrix} 3 \\ 1 \\ 1 \end{pmatrix} ...(1)$$ Now $\begin{pmatrix} \alpha_1 & \alpha_2 & \alpha_3 \\ \beta_1 & \beta_2 & \beta_3 \\ \gamma_1 & \gamma_2 & \gamma_3 \end{pmatrix} \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} = \begin{pmatrix} 1 \\ 3 \\ 1 \end{pmatrix}$. $$\Rightarrow \begin{pmatrix} \alpha_3 \\ \beta_3 \\ \gamma_3 \end{pmatrix} = \begin{pmatrix} 1 \\ 3 \\ 1 \end{pmatrix} ...(2)$$ $A^T \begin{pmatrix} 1 \\ 0 \\ 1 \end{pmatrix} - A^T \begin{pmatrix} 0 \\ 1 \\ 1 \end{pmatrix} = \begin{pmatrix} 5 \\ 2 \\ 2 \end{pmatrix} - \begin{pmatrix} 3 \\ 1 \\ 1 \end{pmatrix}$. $$\Rightarrow A^T \begin{pmatrix} 1 \\ 0 \\ 0 \end{pmatrix} = \begin{pmatrix} 2 \\ 1 \\ 1 \end{pmatrix}$$ $$\begin{pmatrix} \alpha_1 \\ \alpha_2 \\ \alpha_3 \end{pmatrix} = \begin{pmatrix} 2 \\ 1 \\ 1 \end{pmatrix} ...(3)$$ Now $A \begin{pmatrix} 1 \\ 0 \\ 1 \end{pmatrix} - A \begin{pmatrix} 0 \\ 1 \\ 1 \end{pmatrix} = \begin{pmatrix} 4 \\ 4 \\ 4 \end{pmatrix} - \begin{pmatrix} 3 \\ 3 \\ 1 \end{pmatrix}$. $$\Rightarrow A \begin{pmatrix} 1 \\ 0 \\ 0 \end{pmatrix} = \begin{pmatrix} 2 \\ 1 \\ 0 \end{pmatrix}$$ $$\Rightarrow \begin{pmatrix} \alpha_1 \\ \beta_1 \\ \gamma_1 \end{pmatrix} = \begin{pmatrix} 2 \\ 1 \\ 3 \end{pmatrix} ...(4)$$ $A = \begin{pmatrix} 2 & 1 & 1 \\ 1 & \beta_2 & 3 \\ 3 & 1 & 1 \end{pmatrix}$. $|A| = 2(\beta_2 - 3) - 1(1 - 9) + 1(1 - 3\beta_2) = 1$. $$\Rightarrow 2\beta_2 - 6 + 8 + 1 - 3\beta_2 = 1$$ $$\Rightarrow \beta_2 = 2$$ So $A = \begin{pmatrix} 2 & 1 & 1 \\ 1 & 2 & 3 \\ 3 & 1 & 1 \end{pmatrix}$. $A^2 = \begin{pmatrix} 2 & 1 & 1 \\ 1 & 2 & 3 \\ 3 & 1 & 1 \end{pmatrix} \begin{pmatrix} 2 & 1 & 1 \\ 1 & 2 & 3 \\ 3 & 1 & 1 \end{pmatrix} = \begin{pmatrix} 8 & 5 & 6 \\ 13 & 8 & 10 \\ 10 & 6 & 7 \end{pmatrix}$. $A^2 + A = \begin{pmatrix} 10 & 6 & 7 \\ 14 & 10 & 13 \\ 13 & 7 & 8 \end{pmatrix} \Rightarrow \det(A^2 + A) = 8$. $$\Rightarrow Det(adj(A^2 + A)) = 8^2 = 64$$

Question 4

Maths · Determinants · Single correct

Consider the system of linear equations in $x, y, z$: $$x + 2y + tz = 0,$$ $$6x + y + 5tz = 0,$$ $$3x + t^2y + f(t)z = 0,$$ Where $f : \mathbb{R} \to \mathbb{R}$ is a differentiable function. If this system has infinitely many solutions for all $t \in \mathbb{R}$, then $f$

  1. is a constant function
  2. is strictly increasing on $\mathbb{R}$
  3. is strictly decreasing on $\mathbb{R}$
  4. has two critical points

Answer: (b)

Solution

The determinant is given by $$ \begin{vmatrix} 1 & 2 & t \\ 6 & 1 & 5t \\ 3 & t^2 & f(t) \end{vmatrix} = 0 $$ which implies $$ 1(f(t) - 5t^3) - 2(6f(t) - 15t) + t(6t^2 - 3) = 0. $$ Solving for $f(t)$, we get $$ f(t) = \frac{t^3 + 12t}{11}. $$ The derivative is $$ f'(t) = \frac{1}{11}(3t^2 + 12) > 0 \forall \ t \in \mathbb{R}. $$ Therefore, $f(t)$ is strictly increasing on $\mathbb{R}$.

Question 5

Maths · Sequences and Series · Single correct

$\sum_{n=1}^{10} \left( \frac{528}{n(n+1)(n+2)} \right)$ is equal to :

  1. 65
  2. 130
  3. 220
  4. 440

Answer: (b)

Solution

Let $\sum_{n=1}^{10} \frac{528}{n(n+1)(n+2)} = \lambda$. Let $T_n = \frac{1}{n(n+1)(n+2)}$. $$T_n = \frac{1}{2} \left\{ \frac{(n+2)-n}{n(n+1)(n+2)} \right\}$$ $$T_n = \frac{1}{2} \left\{ \frac{1}{n(n+1)} - \frac{1}{(n+1)(n+2)} \right\}$$ $$T_1 = \frac{1}{2} \left\{ \frac{1}{1 \cdot 2} - \frac{1}{2 \cdot 3} \right\}$$ $$T_2 = \frac{1}{2} \left\{ \frac{1}{2 \cdot 3} - \frac{1}{3 \cdot 4} \right\}$$ $$\vdots$$ $$T_{10} = \frac{1}{2} \left\{ \frac{1}{10 \cdot 11} - \frac{1}{11 \cdot 12} \right\}$$ $$S_n = \frac{1}{2} \left[ \frac{1}{2} - \frac{1}{132} \right]$$ $$S_n = \frac{1}{2} \left[ \frac{66 - 1}{132} \right] = \frac{65}{264}$$ So, $\lambda = \frac{65}{264} \times 528$ $\lambda = 130$

Question 6

Maths · Complex Numbers and Quadratic Equations · Single correct

Let $\tan A$, $\tan B$, where $A, B \in \left( -\frac{\pi}{2}, \frac{\pi}{2} \right)$, be the roots of the quadratic equation $x^2 - 2x - 5 = 0$. Then $20 \sin^2 \left( \frac{A + B}{2} \right)$ is equal to:

  1. 10 + $\sqrt{10}$
  2. 10 - 2$\sqrt{10}$
  3. 10 - 3$\sqrt{10}$
  4. 10 - $\sqrt{10}$

Answer: (c)

Solution

Given $x^2 - 2x - 5 = 0$. $\tan A + \tan B = 2$; $\tan A \tan B = -5$. Therefore, $\tan(A + B) = \frac{2}{1 - (-5)} = \frac{1}{3}$. Thus, $\cos(A + B) = \frac{3}{\sqrt{10}}$. Therefore, $20 \left( \sin^2 \left( \frac{A + B}{2} \right) \right) = \frac{10}{2} (1 - \cos(A + B))$. This simplifies to $10 \left( 1 - \frac{3}{\sqrt{10}} \right) = (10 - 3 \sqrt{10})$.

Question 7

Maths · Probability · Single correct

A letter is known to have arrived by post either from KANPUR or from ANANTPUR. On the the envelope just two consecutive letters AN are visible. The probability, that the letter came from ANANTPUR, is:

  1. $\frac{7}{10}$
  2. $\frac{10}{17}$
  3. $\frac{12}{19}$
  4. $\frac{7}{19}$

Answer: (b)

Solution

P(I) : $\frac{1}{2}$ P(A/I) $\rightarrow \frac{1}{5}$ P(II) : $\frac{1}{2}$ P(A/II) $\rightarrow \frac{2}{7}$ $\therefore$ Reqd. Prob = $\frac{\frac{1}{2} \times \frac{2}{7}}{\frac{1}{2} \times \frac{1}{5} + \frac{1}{2} \times \frac{2}{7}}$ = $\frac{\frac{2}{7} \times 5}{\frac{17}{7}}$ = $\frac{10}{17}$

Question 8

Maths · Statistics · Single correct

The mean deviation about the mean for the data is equal to:

  1. $\frac{40}{13}$
  2. $\frac{42}{13}$
  3. $\frac{44}{13}$
  4. $\frac{46}{13}$

Answer: (c)

Solution

The mean deviation (M.D.) is given by the formula: $$ M.D. = \frac{\sum f_i \left| x_i - \bar{x} \right|}{\sum f_i} $$ First, calculate the mean $\bar{x}$: $$ \bar{x} = \frac{\sum f_i x_i}{\sum f_i} = \frac{40 + 42 + 18 + 20 + 24 + 90}{26} $$ This simplifies to: $$ \frac{234}{26} = 9 $$ Now, calculate the mean deviation: $$ M.D. = \frac{8(4) + 6(2) + 2(0) + 2(1) + 2(3) + 6(6)}{26} $$ This simplifies to: $$ \frac{84}{26} = \frac{44}{13} $$

Question 9

Maths · Conic Sections · Single correct

Let a focus of the ellipse E : $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$ be $S(4, 0)$ and its eccentricity be $\frac{4}{5}$. If the point $P(3, \alpha)$ lies on E and O is the origin, then the area of $\Delta POS$ is equal to :

  1. 12/5
  2. 14/5
  3. 24/5
  4. 48/5

Answer: (c)

Solution

Given $a > b$. Focus $(ae, 0) = (4, 0)$. Therefore, $ae = 4$. $$a \left( \frac{4}{5} \right) = 4 \implies a = 5$$ Thus, $b^2 = a^2 (1 - e^2)$. $$b^2 = 25 \left( 1 - \frac{16}{25} \right)$$ Therefore, $E : \frac{x^2}{25} + \frac{y^2}{9} = 1$. Thus, $P$ lies on the ellipse $E$. $$\frac{9}{25} + \frac{\alpha^2}{9} = 1$$ Therefore, $\alpha = \pm \frac{12}{5}$. Thus, the area of $\Delta_{POS} = \frac{1}{2} (OS)(PN)$. $$= \frac{1}{2} \times 4 \times \frac{12}{5} = \frac{24}{5}$$

Question 10

Maths · Conic Sections · Single correct

Let P be a moving point on the circle $x^2 + y^2 - 6x - 8y + 21 = 0$ Then, the maximum distance of P from the vertex of the parabola $x^2 + 6x + y + 13 = 0$ is equal to :

  1. 8
  2. 10
  3. 12
  4. 9

Answer: (c)

Solution

Centre: $C(3,4)$ and $r = 2$. Parabola $(x + 3)^2 = -(y + 4)$. Vertex is $A(-3,-4)$. $$AP_{max} = AC + r = \sqrt{36 + 64} + 2 = 12$$

Question 11

Maths · Properties of Triangles · Single correct

In an equilateral triangle PQR, let the vertex P be at (3, 5) and the side QR be along the line $x + y = 4$. If the orthocentre of the triangle PQR is $(\alpha, \beta)$, then $9(\alpha + \beta)$ is equal to :

  1. 16
  2. 27
  3. 36
  4. 48

Answer: (d)

Solution

Given the triangle with vertices $P(3,5)$, $Q(1,3)$, and $R$. The line $x+y=4$ is given. For point $Q$: $$\frac{x-3}{1} = \frac{y-5}{1} = \frac{(3+5-4)}{1+1}$$ This gives $Q(1, 3)$. So the orthocenter is $$\left( \frac{2+3}{3}, \frac{6+5}{3} \right)$$ Calculating further: $$\left( \frac{5}{3}, \frac{11}{3} \right)$$ So $9(\alpha + \beta) = 3(16) = 48$

Question 12

Maths · Trigonometric Functions · Single correct

The sum of all the integral values of $p$ such that the equation $3\sin^2 x + 12\cos x - 3 = p$, $x \in \mathbb{R}$, has at least one solution, is:

  1. -54
  2. -60
  3. -75
  4. -84

Answer: (c)

Solution

Given $P = 12 \cos x - 3 \cos^2 x$. $P = -3 (\cos^2 x - 4 \cos x)$ $P = -3 ((\cos x - 2)^2 - 2)$ Put $\cos x = -1$ implies $P = -15$. Put $\cos x = 1$ implies $P = 9$. $-15 \leq P \leq 9$. Sum of all integers $= -(10 + 11 + \ldots + 15) = -75$.

Question 13

Maths · Three Dimensional Geometry · Single correct

The square of the distance of the point P(5, 6, 7) from the line $\frac{x-2}{2} = \frac{y-5}{3} = \frac{z-2}{4}$ is equal to:

  1. 3
  2. 5
  3. 6
  4. 8

Answer: (c)

Solution

Given $\overrightarrow{PQ} \cdot \overrightarrow{A} = 0$. Therefore, $$(2\lambda - 3)2 + (3\lambda - 1)3 + (4\lambda - 5)4 = 0$$ which implies $\lambda = 1$. The point $P$ is $(5, 6, 7)$ and the vector $\overrightarrow{A}$ is $\langle 2, 3, 4 \rangle$. The point $Q$ is given by $(2\lambda + 2, 3\lambda + 5, 4\lambda + 2)$. Substituting $\lambda = 1$, we find Point $Q = (4, 8, 6)$. Therefore, $PQ^2 = 6$.

Question 14

Maths · Vector Algebra · Single correct

Let $\vec{a} = \sqrt{7} \hat{i} + \hat{j} - \hat{k}$ and $\vec{b} = \hat{j} + 2 \hat{k}$. If $\vec{r}$ is a vector such that $\vec{r} \times \vec{a} + \vec{a} \times \vec{b} = \vec{0}$ and $\vec{r} \cdot \vec{a} = 0$, then $|3 \vec{r}|^2$ is equal to:

  1. 44
  2. 54
  3. 86
  4. 132

Answer: (a)

Solution

Given $\vec{r} \times \vec{a} - \vec{b} \times \vec{a} = \vec{0}$. $$(\vec{r} - \vec{b}) \times \vec{a} = \vec{0}$$ $$\vec{r} - \vec{b} = \lambda \vec{a}$$ $$\vec{r} = \vec{b} + \lambda \vec{a}$$ $$\vec{r} \cdot \vec{a} = 0 \implies \vec{a} \cdot \vec{b} + \lambda |\vec{a}|^2 = 0$$ $$\lambda = -\frac{\vec{a} \cdot \vec{b}}{|\vec{a}|^2} = -\frac{(1-2)}{9} = \frac{1}{9}$$ $$\vec{r} = \vec{b} + \frac{\vec{a}}{9}$$ $$|3\vec{r}|^2 = 9|\vec{r}|^2 = 9 \left( b^2 + \frac{a^2}{81} + \frac{2(\vec{a} \cdot \vec{b})}{9} \right) = 44$$

Question 15

Maths · Three Dimensional Geometry · Single correct

The square of the distance of the point of intersection of the lines $\vec{r} = (\hat{i} + \hat{j} - \hat{k}) + \lambda (a \hat{i} - \hat{j})$, $a \neq 0$ and $\vec{r} = (4 \hat{i} - \hat{k}) + \mu (2 \hat{i} + a \hat{k})$ from the origin is:

  1. 5
  2. 10
  3. 17
  4. 26

Answer: (c)

Solution

Equating both the equations $$ (\hat{i} + \hat{j} - \hat{k}) + \lambda (a\hat{i} - \hat{j}) = (4\hat{i} - \hat{k}) + \mu (2\hat{i} + a\hat{k}) $$ $$ 1 + a\lambda = 4 + 2\mu $$ $$ 1 - \lambda = 0 \Rightarrow \lambda = 1 $$ $$ -1 = -1 + a\mu $$ $$ a\mu = 0 \Rightarrow \mu = 0 $$ $$ a = 3 $$ point of intersection $$ = \hat{i} + \hat{j} - \hat{k} + 3\hat{i} - \hat{j} = 4\hat{i} - \hat{k} $$

Question 16

Maths · Applications of Integrals · Single correct

The area of the region R = $\{$(x,y): xy $\leq$ 27, 1 $\leq$ y $\leq$ x^2$\}$ is equal to:

  1. 78 $\log_e$ 3 - $\frac{52}{3}$
  2. 54 $\log_e$ 3 - $\frac{52}{3}$
  3. 54 $\log_e$ 3 - $\frac{26}{3}$
  4. 54 $\log_e$ 3 + $\frac{26}{3}$

Answer: (b)

Solution

The area is given by the integral: $$\int_{1}^{3} (x^2 - 1) \, dx + \int_{3}^{27} \left( \frac{27}{x} - 1 \right) \, dx$$ This simplifies to: $$\left[ \frac{x^3}{3} - x \right]_{1}^{3} + \left[ 27 \ln x - x \right]_{3}^{27}$$ Evaluating the integrals, we get: $$= \frac{26}{3} - 2 + 27 \ln 9 - 24$$ Simplifying further: $$= 27 \ln 9 - \frac{26 \times 2}{3}$$ Finally, we have: $$= 54 \ln 3 - \frac{52}{3}$$

Question 17

Maths · Limits and Derivatives · Single correct

The product of all possible values of $\alpha$, for which $$\lim_{x \to 0} \left( \frac{1 - \cos(\alpha x) \cos((\alpha + 1)x) \cos((\alpha + 2)x)}{\sin^2((\alpha + 1)x)} \right) = 2,$$ is :

  1. $-2$
  2. $1$
  3. $-1$
  4. $\frac{5}{4}$

Answer: (c)

Solution

By using L.H. Rule we get $$\Rightarrow \frac{1}{2}(\alpha + 1)^2 [\alpha^2 + (\alpha + 1)^2 + (\alpha + 2)^2] = 2$$ $$\alpha^2 + (\alpha + 1)^2 + (\alpha + 2)^2 = 4(\alpha + 1)^2$$ $$\alpha^2 + (\alpha + 2)^2 = 3(\alpha + 1)^2$$ $$\Rightarrow \alpha^2 + 2\alpha - 1 = 0$$ Product $= -1$

Question 18

Maths · Integrals · Single correct

The value of the integral $\int_{0}^{\infty} \frac{\log_e(x)}{x^2 + 4} \, \mathrm{dx}$ is:

  1. $\frac{\pi \log_e(2)}{2}$
  2. $\frac{\pi \log_e(2)}{4}$
  3. 1 + $\pi \log_e$(2)
  4. 2 + $\pi \log_e$(2)

Answer: (b)

Solution

Put $x = 2t \Rightarrow dx = 2dt$ $$I = \int_0^\infty \frac{\ln 2t}{4t^2 + 4} (2dt) = \frac{1}{2} \int_0^\infty \frac{\ln 2 + \ln t}{t^2 + 1} dt$$ $$= \frac{1}{2} \int_0^\infty \frac{\ln 2}{t^2 + 1} dt + \frac{1}{2} \int_0^\infty \frac{\ln t}{t^2 + 1} dt$$ $$= \left[ \frac{\ln 2}{2} \tan^{-1} t \right]_0^\infty + I_1$$ $$= \frac{\ln 2}{2} \cdot \frac{\pi}{2} + I_1$$ $$I_2 = \frac{1}{2} \int_0^\infty \frac{\ln t}{t^2 + 1} dt t = \frac{1}{u} \Rightarrow dt = -\frac{du}{u^2}$$ $$= \frac{1}{2} \int_\infty^0 \frac{\ln (1/u)}{1/u^2 + 1} \left( -\frac{du}{u^2} \right)$$ Add $\Rightarrow I_1 = 0$ $$I = \frac{\pi \ln 2}{4}$$

Question 19

Maths · Continuity and Differentiability · Single correct

Let $f : \mathbb{R} \to \mathbb{R}$ be a differentiable function such that $$f\left( \frac{x+y}{3} \right) = \frac{f(x) + f(y)}{3}$$ for all $x, y \in \mathbb{R}$ and $f'(0) = 3$. Then the minimum value of the function $g(x) = 3 + e^x f(x)$, is

  1. $3\left( \frac{e+1}{e} \right)$
  2. $3\left( \frac{e-1}{e} \right)$
  3. $\frac{3-e}{e}$
  4. $3e$

Answer: (b)

Solution

Given $f\left( \frac{x+y}{3} \right) = \frac{f(x) + f(y)}{3}$, put $x = y = 0$. $f(0) = \frac{2f(0)}{3}$ $\Rightarrow f(0) = 0 \ldots (1)$ $f'\left( \frac{x+y}{3} \right) \cdot \frac{1}{3} = \frac{1}{3} f'(x)$ Put $x = 0$ $f'\left( \frac{y}{3} \right) \frac{1}{3} = \frac{1}{3} \times 3$ $f'\left( \frac{y}{3} \right) = 3$ Put $y = 3x$ $f'(x) = 3$ Integrate both sides $f(x) = 3x + c$ From eq. (1) $f(0) = 0$ $\Rightarrow f(x) = 3x$ Now $g(x) = 3 + e^x \cdot 3x$ $g'(x) = 3[e^x + x \cdot e^x]$ $= 3e^x(x + 1)$ $g'(x) = 0$, at $x = -1$ $(g(x))_{\min} = 3 + e^{-1}(-3)$ $= 3 \left[ 1 - \frac{1}{e} \right] = \frac{3(e-1)}{e}$

Question 20

Maths · Integrals · Single correct

The value of the integral $\int_{\pi/6}^{\pi/3}\left(\frac{4-\operatorname{cosec}^2x}{\cos^4x}\right)dx$ is:

  1. $\frac{11}{\sqrt{3}}$
  2. $\frac{16}{\sqrt{3}}$
  3. $\frac{32}{3\sqrt{3}}$
  4. $\frac{64}{3\sqrt{3}}$

Answer: (c)

Solution

The solution is given by the integral: $$ \int_{\pi/6}^{\pi/3} \frac{4}{\cos^4 x} \, dx - \int_{\pi/6}^{\pi/3} \frac{\csc^2 x}{\cos^4 x} \, dx $$ This can be rewritten as: $$ \int_{\pi/6}^{\pi/3} \frac{4}{\cos^4 x} \, dx - \left[ -\frac{\cot x}{\cos^4 x} \right]_{\pi/6}^{\pi/3} - \int_{\pi/6}^{\pi/3} (-\cot x) \frac{-4}{\cos^5 x} (-\sin x) \, dx $$ Simplifying further: $$ = \frac{\cot x}{\cos^4 x} \bigg|_{\pi/6}^{\pi/3} $$ Evaluating the expression: $$ = \frac{1/\sqrt{3}}{(1/2)^4} - \frac{\sqrt{3}}{\left(\frac{\sqrt{3}}{2}\right)^4} $$ This simplifies to: $$ = \frac{16}{\sqrt{3}} - \frac{\sqrt{3} \cdot 16}{9} = \frac{16}{\sqrt{3}} - \frac{16}{3\sqrt{3}} = \frac{16}{\sqrt{3}} \left(1 - \frac{1}{3}\right) $$ Finally, we have: $$ \frac{32}{3\sqrt{3}} = \frac{32\sqrt{3}}{9} $$

Question 21

Maths · Permutations and Combinations · Numerical

Let $A = \{1, 2, 3, 4, 5, 6\}$. The number of one-one functions $f : A \to A$ such that $f(1) \geq 3$, $f(3) \leq 4$ and $f(2) + f(3) = 5$, is $\ldots$.

Answer: 72

Solution

Given $f(2) + f(3) = 5$. C-I: $f(2) = 4$, $f(3) = 1$ So, $f(1) = 3, 5, 6 \rightarrow 3$ choices. $f(4) \rightarrow 3$ choices. $f(5) \rightarrow 2$ choices. $f(6) \rightarrow 1$ choice. So total function for C-I: $3 \times 3 \times 2 \times 1 = 18$. Similarly C-II: $f(2) = 1$, $f(3) = 4 \rightarrow 18$ function. C-III: $f(2) = 3$, $f(3) = 2 \rightarrow 18$ function. C-IV: $f(2) = 2$, $f(3) = 2 \rightarrow 18$ function. Answer total 72 function.

Question 22

Maths · Permutations and Combinations · Numerical

Two players A and B play a series of games of badminton. The player, who wins 5 games first, wins the series. Assuming that no game ends in a draw, the number of ways, in which player A wins the series is $\ldots$.

Answer: 126

Solution

Maximum number of games will be 9. A must win 5 games so, Number of ways = $$^9C_5 = 126$$ Answer = 126

Question 23

Maths · Binomial Theorem · Numerical

If the sum of the coefficients of $x^7$ and $x^{14}$ in the expansion of $$\left(\frac{1}{x^3} - x^4\right)^n$$, $x \neq 0$, is zero, then the value of $n$ is $\ldots$.

Answer: 21

Solution

Given $T_{r+1} = \binom{n}{r} \left( \frac{1}{x^3} \right)^{n-r} (-x^4)^r$. $T_{r+1} = \binom{n}{r} x^{7r-3n} (-1)^r$. For the coefficient of $x^7$, $7r_1 - 3n = 7$. $$\Rightarrow r_1 = \frac{7 + 3n}{7}$$ Coefficient of $x^7 \Rightarrow \binom{n}{r_1} (-1)^{r_1}$. For the coefficient of $x^{14}$, $7r_2 - 3n = 14$. $$\Rightarrow r_2 = \frac{14 + 3n}{7} = r_1 + 1$$ Coefficient of $x^{14} \Rightarrow \binom{n}{r_1+1} (-1)^{r_1+1}$. $$\Rightarrow \binom{n}{r_1} (-1)^{r_1} + \binom{n}{r_1+1} (-1)^{r_1+1} = 0$$ $$\Rightarrow \binom{n}{r_1} = \binom{n}{r_1+1} \Rightarrow r_1 + r_1 + 1 = n$$ $$\Rightarrow 2r_1 + 1 = n \Rightarrow 2 \left( \frac{7 + 3n}{7} \right) + 1 = n$$ Ans. $\Rightarrow n = 21$

Question 24

Maths · Inverse Trigonometric Functions · Numerical

If $\frac{\pi}{4} + \sum_{p=1}^{11} \tan^{-1} \left( \frac{2^{p-1}}{1 + 2^{2p-1}} \right) = \alpha$, then $\tan \alpha$ is equal to $\ldots$.

Answer: 2048

Solution

Given $$\alpha = \frac{\pi}{4} + \sum_{p=1}^{11} \tan^{-1} \left( \frac{2^{p-1}}{1 + 2^{2p-1}} \right)$$ This simplifies to $$= \frac{\pi}{4} + \sum_{p=1}^{11} \tan^{-1} \left( \frac{2^p - 2^{p-1}}{1 + 2^{2p-1}} \right)$$ Further simplifying, we have $$= \frac{\pi}{4} + \sum_{p=1}^{11} \left( \tan^{-1} \left( 2^p \right) - \tan^{-1} \left( 2^{p-1} \right) \right)$$ Finally, $$= \frac{\pi}{4} + \tan^{-1} \left( 2^{11} \right) - \tan^{-1} \left( 2^0 \right) = 2^{11}$$ The answer is 2048.

Question 25

Maths · Differential Equations · Numerical

Let $y = y(x)$ be the solution of the differential equation $x \sin \left( \frac{y}{x} \right) \mathrm{d}y = \left( y \sin \left( \frac{y}{x} \right) - x \right) \mathrm{d}x$, $y(1) = \frac{\pi}{2}$ and let $\alpha = \cos \left( \frac{y \left( e^{12} \right)}{e^{12}} \right)$. Then the number of integral value of $p$, for which the equation $x^2 + y^2 - 2px + 2py + \alpha + 2 = 0$ represents a circle of radius $r \leq 6$, is $\ldots$.

Answer: 11

Solution

Given $\sin \frac{y}{x} \frac{dy}{dx} = \frac{y}{x} \sin \frac{y}{x} - 1$. Put $y = tx$ which implies $\frac{dy}{dx} = t + x \frac{dt}{dx}$. Then, $\sin t \left( t + x \frac{dt}{dx} \right) = t \sin t - 1$. This gives $x \sin t \frac{dt}{dx} + 1 = 0$. Therefore, $\sin t \, dt + \frac{dx}{x} = 0$. Integrating, we get $-\cos t + \ln x = C$. Substituting back, $-\cos \left( \frac{y}{x} \right) + \ln x = C$. Given $y(1) = \frac{\pi}{2}$, we find $C = 0$. Thus, $\cos \left( \frac{y}{x} \right) = \ln x$. Solving $\csc \left( \frac{y(e^{12})}{e^{12}} \right) = 12$, we find $\alpha = 12$. For the equation $x^2 + y^2 - 2px + 2py + 14 = 0$, we have $r = \sqrt{p^2 + p^2 - 14}$. This implies $r \leq 6 \Rightarrow r^2 \leq 36$. Therefore, $2p^2 - 14 \leq 36$, which simplifies to $p^2 \leq 25$. Hence, $p \in [-5, 5]$. The number of integral values of $p$ is 11.

Physics

Question 26

Physics · Physical World, Units and Measurements · Single correct

In a Vernier calipers, when both jaws touch each other, zero of the Vernier scale is shifted to the right of zero of the main scale and 7^{th} Vernier division coincides with a main scale reading. If the value of 1 main scale division is $1\,\mathrm{mm}$ and there are 10 Vernier scale divisions, then the Vernier caliper has

  1. $0.07\,\mathrm{cm}$ negative zero error
  2. $0.7\,\mathrm{cm}$ negative zero error
  3. $0.07\,\mathrm{cm}$ positive zero error
  4. $0.7\,\mathrm{cm}$ positive zero error

Answer: (c)

Solution

Scale reading = main scale + Least count $\times$ V.S.R. $$= 0 + \frac{1}{10} \times 7 = 0.7 \, \mathrm{mm}$$ $$= 0.07 \, \mathrm{cm}$$

Question 27

Physics · Physical World, Units and Measurements · Single correct

L, C and R represents physical quantities inductance, capacitance and resistance respectively. The dimensional formula $M L^2 T^{-4} A^{-2}$ corresponds to $\ldots$.

  1. $\frac{R}{\sqrt{LC}}$
  2. $\frac{R}{LC}$
  3. $\frac{C}{\sqrt{LR}}$
  4. $\frac{1}{R} \sqrt{\frac{L}{C}}$

Answer: (a)

Solution

Given $R = \frac{V}{I} = \frac{w}{qI} = \frac{ML^2T^{-2}}{I^2T} = ML^2T^{-3}I^{-2}$ $U = \frac{1}{2}LI^2 \rightarrow ML^2T^{-2} = LA^2$ $L = ML^2T^{-2}A^{-2}$ $Q = CV$ $C = \frac{IT \times q}{ML^2T^{-2}} = \frac{A^2T^2}{ML^2T^{-2}}$ $C = M^{-1}L^{-2}A^{-2}T^4$ $LC = ML^2T^{-2}A^{-2} \times M^{-1}L^{-1}A^2T^4$ $LC = T^2$ $\frac{R}{\sqrt{LC}} = \frac{ML^2T^{-3}A^{-2}}{T} = (ML^2T^4A^{-2})$

Question 28

Physics · Gravitation · Single correct

When one moves from a point 16 km below the earth's surface to a point 16 km above the earth's surface. The change in $g$ is approximately $\alpha \%$. The value of $\alpha$ is $\ldots$. (Take radius of the earth $= 6400$ km.)

  1. 0.12
  2. 0.25
  3. 0.50
  4. 0.75

Answer: (b)

Solution

Given $$g_{above} = g - \frac{2hg}{R} = 10 - \frac{2h}{R}$$ $$g_{below} = g - \frac{hg}{R}$$ $$\Delta g = g_{above} - g_{below} = g - \frac{2hg}{R} - g + \frac{hg}{R}$$ $$\Delta g = \frac{hg}{R}$$ $$\frac{\Delta g}{g} = \frac{h}{R} = \frac{16 \times 100}{6400} = 0.25\%$$

Question 29

Physics · Laws of Motion · Single correct

Three masses $m_1 = 4 \, \mathrm{kg}$, $m_2 = 4 \, \mathrm{kg}$ and $m_3 = 6 \, \mathrm{kg}$ are suspended from a fixed smooth frictionless pulley as shown in the figure below. The value of $T_1 / T_2$ is $\ldots$. (take $g = 10 \, \mathrm{m/s^2}$)

  1. $\frac{5}{3}$
  2. $\frac{2}{3}$
  3. $\frac{3}{5}$
  4. $\frac{2}{5}$

Answer: (a)

Solution

Given the equations: $$60 - T_2 = 6a$$ $$T_2 + 40 - T_1 = 4a$$ $$60 = 14a$$ Solving for $a$: $$a = \frac{60}{14} = \frac{30}{7}$$ Substituting $a$ into the equation for $T_1$: $$T_1 = 40 + 4 \times \frac{30}{7} = \frac{280 + 120}{7}$$ $$T_1 = \frac{400}{7}$$ Substituting $a$ into the equation for $T_2$: $$60 - T_2 = 6 \times \frac{30}{7}$$ $$60 - \frac{180}{7} = T_2$$ $$\frac{420 - 180}{7} = T_2 = \frac{240}{7}$$ Finally, the ratio of $T_1$ to $T_2$ is: $$\frac{T_1}{T_2} = \frac{5}{3}$$

Question 30

Physics · Laws of Motion · Single correct

A wedge Y with mass of $10\,\mathrm{kg}$ and all frictionless surfaces and the inclined surface making $37^\circ$ with horizontal. A block X with mass $2\,\mathrm{kg}$ is placed at the highest point of the wedge as shown in figure is at rest. At $t=0$ wedge (Y) is pulled toward right with constant force ($f$) of $24\,\mathrm{N}$. Taking the block X at rest at $t=0$, the time taken by it to slide down $8.8\,\mathrm{m}$ on the slope, while Y is on the move, is $\underline{\hspace{1cm}}$ s. (take $\tan(37^\circ)=3/4$ and $g=10\,\mathrm{m/s^2}$)

  1. 2
  2. 4
  3. $\sqrt{2}$
  4. 2$\sqrt{2}$

Answer: (a)

Solution

Given the diagrams, we start with the equations: $$20 \sin 37^\circ - 2a_\omega \cos 37^\circ = 2a_{rel}$$ $$20 \cos 37^\circ - N + 2a_\omega \sin 37^\circ = 0$$ $$24 - N \sin 37^\circ = 10 \times a_\omega$$ Solving the equations: $$24 - (20 \cos 37^\circ + 2a_\omega \sin 37^\circ) \times \sin 37^\circ = 10a_\omega$$ $$24 - \left(16 + 2a_\omega \times \frac{3}{5}\right) \frac{3}{5} = 10a_\omega$$ $$24 - \frac{48}{5} - \frac{18}{25} a_\omega = 10a_\omega$$ $$\frac{72}{5} = \left(10 - \frac{18}{25}\right) a_\omega$$ $$\frac{72}{5} = a_\omega = \frac{180}{116} = \frac{90}{58}$$ $$a_\omega = \frac{45}{29}$$ Substituting back: $$20 \sin 37^\circ - 2 \times \frac{45}{29} \times \frac{4}{5} \times \cos 37^\circ = 2a_{rel}$$ $$12 - \frac{72}{29} = 2a_{rel}$$ $$\frac{348 - 72}{29} = 2a_{rel}$$ $$\frac{276}{29 \times 2} = a_{rel}; \frac{138}{29} = a_{rel}$$ Calculating time $t$: $$t = \sqrt{\frac{2 \times 8.8 \times 29}{138}}$$ $$t = \sqrt{\frac{2 \times 8.8 \times 29}{10 \times 138}}$$ $$t = \sqrt{3.69}$$ $$t \approx 2 sec$$ After rounding off.

Question 31

Physics · Mechanical Properties of Solids · Single correct

The Young's modulus of steel wire of radius $r$ and length $L$ is $Y$. If the radius $r$ and length $L$ of the wire are doubled then the value of $Y$

  1. increases by two times
  2. reduces by half
  3. remains unchanged
  4. becomes one fourth

Answer: (c)

Solution

Young's modulus is the property of material not depends on dimensions of material.

Question 32

Physics · Kinetic Theory · Single correct

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Statement I : Change in internal energy of a system containing n mole of ideal gas can be written as $\Delta U = nC_v(T_f - T_i) = \frac{nR}{\gamma - 1}(T_f - T_i)$, where $\gamma = \frac{C_p}{C_v}$, $T_i =$ initial temperature, $T_f =$ final temperature. Statement II : Relation between degree of freedom $f$ and $\gamma ( = C_p/C_v)$ is $\left( \gamma = 1 + \frac{2}{f} \right)$ Choose the correct answer from the options given below

  1. Both A and R are true and R is the correct explanation of A
  2. Both A and R are true but R is NOT the correct explanation of A
  3. A is true but R is false
  4. A is false but R is true

Answer: (b)

Solution

Both statements are correct but the second does not explain the first statement.

Question 33

Physics · Thermodynamics · Single correct

Consider the following statements: A. Zeroth law of thermodynamics gives concept of temperature B. First law of thermodynamics gives concept of internal energy C. In isothermal expansion of ideal gas, $\Delta Q \neq \Delta W$ D. Product of intensive and extensive variables is extensive E. The ratio of any extensive variable to mass will be an extensive variable Choose the correct combination of statements from the options given below:

  1. C, D and E Only
  2. A, B and C Only
  3. A, B and D Only
  4. B, C and D Only

Answer: (c)

Solution

Statement A, B and D are correct

Question 34

Physics · Current Electricity · Single correct

Refer to the figure given below. The values of $I_1$, $I_2$ and $I_3$ are $\ldots$.

  1. $I_1 = 2.5 \, \mathrm{A}$, $I_2 = 1.875 \, \mathrm{A}$, $I_3 = 1.875 \, \mathrm{A}$
  2. $I_1 = 1.875 \, \mathrm{A}$, $I_2 = 2.5 \, \mathrm{A}$, $I_3 = 1.875 \, \mathrm{A}$
  3. $I_1 = 1.875 \, \mathrm{A}$, $I_2 = 1.875 \, \mathrm{A}$, $I_3 = 2.5 \, \mathrm{A}$
  4. $I_1 = 2.5 \, \mathrm{A}$, $I_2 = 2.5 \, \mathrm{A}$, $I_3 = 1.875 \, \mathrm{A}$

Answer: (a)

Solution

Loop-1: $$-4 \left(i_1 - i_3\right) - 2 \left(i_1 + i_2 - i_3\right) - i_1 + 10 = 0$$ $$-7i_1 - 2i_2 + 6i_3 + 10 = 0 \ldots(1)$$ Loop-2: $$-5 - 2 \left(i_3 - i_2\right) + 2 \left(i_1 + i_2 - i_3\right) = 0$$ $$2i_1 + 4i_2 - 4i_3 - 5 = 0 \ldots(2)$$ Loop-3: $$-i_1 + 10 - 4i_3 - 2 \left(i_3 - i_2\right) = 0$$ $$2i_2 - 6i_3 - i_1 + 10 = 0 \ldots(3)$$ On solving equation- (i) & (ii) & (iii) $$i_1 = 2.5 \, \mathrm{A}$$ $$i_2 = 1.875 \, \mathrm{A}$$ $$i_3 = 1.875 \, \mathrm{A}$$

Question 35

Physics · Dual Nature of Radiation and Matter · Single correct

An electron of mass $m$ is moving in an electric field $\vec{E} = -2E_0 \hat{i}$ ($E_0 = constant > 0$), with an initial velocity $\vec{V} = v_0 \hat{i}$ ($v_0 = constant > 0$). If $\lambda_0 = \frac{h}{4mv_0}$, its de Broglie wavelength at time $t$ is $\ldots$. (e = charge of electron)

  1. $\frac{4\lambda_0}{\left[1 - \frac{E_0 e \, t}{2m \, v_0}\right]}$
  2. $\frac{4\lambda_0}{\left[1 + \frac{E_0 e \, t}{2m \, v_0}\right]}$
  3. $\frac{4\lambda_0}{\left[1 + \frac{2E_0 e \, t}{m \, v_0}\right]}$
  4. $\frac{4\lambda_0}{\left[1 - \frac{2E_0 e \, t}{m \, v_0}\right]}$

Answer: (c)

Solution

Given $V = U + at$. $V = V_0 + \left( \frac{2eE_0}{m} \right)t$ Therefore, $a = \frac{(2E_0)e}{m}$ $\lambda = \frac{h}{mV}$ $\lambda = \frac{h}{m \left[ V_0 + \frac{2eE_0}{m}t \right]}$ Put $\lambda_0 = \frac{h}{4mV_0}$ which implies $h = 4\lambda_0 m V_0$ $\lambda = \frac{4m\lambda_0 V_0}{m \left[ V_0 + \frac{2eE_0}{m}t \right]}$ $\lambda = \frac{4\lambda_0}{1 + \frac{2eE_0}{mV_0}t}$

Question 36

Physics · Atoms · Single correct

In the hydrogen atom, the electron makes a transition from the higher orbit (i) to a lower orbit (f). The ratio of the radius of the orbits in given by $r_i : r_f = 16 : 4$. The wavelength of photon emitted due to this transition is ___ nm. (Given Rydberg constant = $1.0973 \times 10^7 / \mathrm{m}$)

  1. 121
  2. 242
  3. 486
  4. 974

Answer: (c)

Solution

Given: $\frac{r_i}{r_f} = \frac{16}{4} = \frac{n_1^2}{n_f^2}$ $\frac{n_i}{n_f} = \frac{4}{2}$ $$\frac{1}{\lambda} = \mathrm{R} \left( \frac{1}{n_f^2} - \frac{1}{n_i^2} \right) = 1.0973 \times 10^7 \left( \frac{1}{(2)^2} - \frac{1}{(4)^2} \right)$$ $\lambda = 4.86 \times 10^{-7} \, \mathrm{m} \approx 486 \, \mathrm{nm}$

Question 37

Physics · Electromagnetic Waves · Single correct

A displacement current of $4.0\,\mathrm{A}$ can be set up in the space between two parallel plates of 6 $\mu \mathrm{F}$ capacitor. The rate of change of potential difference across the plates of the capacitor is nearly $\alpha \times 10^6 \, \mathrm{V/s}$. The value of $\alpha$ is $\ldots$.

  1. 0.58
  2. 0.67
  3. 0.82
  4. 0.75

Answer: (b)

Solution

Given $I_d = C \frac{dV}{dt}$. $$4 = (6 \times 10^{-6})(\alpha \times 10^6)$$ $$\alpha = \frac{2}{3} \approx 0.67$$

Question 38

Physics · Current Electricity · Single correct

Refer to the figure given below, current between terminals A and B is $\ldots$ A.

  1. 12.5
  2. 1.25
  3. 7.5
  4. 5

Answer: (b)

Solution

Solving each branch as series $$\varepsilon_{eq} = \frac{15}{9} + \frac{15}{9} + \frac{15}{9} = 15 \, volt$$ and $$\frac{1}{r_{eq}} = \frac{1}{9} + \frac{1}{9} + \frac{1}{9}$$ $$r_{eq} = 3 \, \Omega$$ $$I_{AB} = \frac{15}{12} = 1.25 \, A$$

Question 39

Physics · Wave Optics · Single correct

In Young's double slit experiment, the fringe width of the interference pattern produced on the screen is $2.4 \, \mu \mathrm{m}$. If the experiment is carried out in another medium having refractive index $1.2$, the fringe width will be $\ldots \mu \mathrm{m}$.

  1. 1.2
  2. 2
  3. 2.4
  4. 2.88

Answer: (b)

Solution

Since Fringe width in a medium becomes $$\beta' = \frac{\beta}{\mu} \left( Here \beta = \frac{\lambda D}{d} \right)$$ $$\beta' = \frac{\beta}{\mu} = \frac{2.4}{1.2} = 2 \, \mu m$$

Question 40

Physics · Ray Optics and Optical Instruments · Single correct

A ray of light passing through an equilateral prism is having velocity $2.12 \times 10^8 \, \mathrm{m/s}$ in the prism material, then the minimum angle of deviation is $\ldots$ degrees.

  1. 45
  2. 30
  3. 28
  4. 58

Answer: (b)

Solution

Given $\mu = \frac{\sin \left( \frac{\delta_{\min} + A}{2} \right)}{\sin \frac{A}{2}}$. $$\mu = \frac{C}{V} = \frac{3 \times 10^8}{2.12 \times 10^8} = \sqrt{2}$$ $$\sqrt{2} = \frac{\sin \left( \frac{\delta_{\min} + 60^\circ}{2} \right)}{\sin 30^\circ}$$ $$\sin \left( \frac{\delta_{\min} + 60^\circ}{2} \right) = \frac{1}{\sqrt{2}}$$ $\delta_{\min} + 60^\circ = 90^\circ \Rightarrow \delta_{\min} = 30^\circ$

Question 41

Physics · Dual Nature of Radiation and Matter · Single correct

Light source having wavelength $331\,\mathrm{\ nm}$ is used to generate photo-electrons whose stopping potential is $0.2\,\mathrm{\ V}$. The work function of the used metal in the experiment is $\alpha \times$ 10^{-19} $\mathrm{\ J}$. The value of $\alpha$ is $\ldots$. (h = 6.62 $\times$ 10^{-34} $\mathrm{\ Js}$, e = 1.6 $\times$ 10^{-19} $\mathrm{\ C}$ and c = 3 $\times$ 10^{8} $\mathrm{\ m/s}$)

  1. 3.68
  2. 4.68
  3. 5.68
  4. 2.68

Answer: (c)

Solution

Given $V_s = \frac{1}{e} \left( \frac{hc}{\lambda} - \phi \right)$. $\phi = \frac{hc}{\lambda} - eV_s$ $$= \left( \frac{6.62 \times 10^{-34} \times 3 \times 10^8}{331 \times 10^{-9}} \right) - (1.6 \times 10^{-19} \times 0.2)$$ $$= 5.68 \times 10^{-19} \, \mathrm{J}$$

Question 42

Physics · Ray Optics and Optical Instruments · Single correct

A compound microscope is designed with two symmetric biconvex lenses. The objective lens is cut vertically, creating two identical plano-convex lenses. One of them is used in place of original objective lens. To retain same magnification keeping the object distance unchanged, the tube length has to be : -

  1. increased two times
  2. increased $\frac{3}{2}$ times
  3. decreased two times
  4. decreased $\frac{3}{2}$ times

Answer: (a)

Solution

M = $\frac{L}{F_0} \frac{D}{F_e} \newline \frac{1}{F_0}$ = (n-1) $\left( \frac{2}{R} \right) \newline$ But when cut $\newline \frac{1}{F_0'}$ = (n-1) $\left( \frac{1}{R} \right)$ = $\frac{1}{2F_0} \newline$ So, $\frac{L}{F_0}$ = $\frac{L'}{F_0'}$ = 2L

Question 43

Physics · Mechanical Properties of Solids · Single correct

Two wires as shown in the figure below, made of steel and have breaking stress of $12 \times 10^8 \, \mathrm{N/m^2}$. Area of cross-section of upper wire is $0.008 \, \mathrm{cm^2}$ and of lower wire is $0.004 \, \mathrm{cm^2}$. The maximum mass that can be added to pan without breaking any wire is $\ldots$ kg. (take $g = 10 \, \mathrm{m/s^2}$)

  1. 56
  2. 38
  3. 96
  4. 5.6

Answer: (b)

Solution

The tension $T_1 = mg$. The tension $T_2 = (10 + m)g$. The tension $T_3 = (30 + 10 + m)g = g(40 + m)$. Stress in upper wire $$\frac{(40 + m)g}{0.008 \, \mathrm{cm}^2}$$ $$= \frac{(40 + m) \times 10}{8 \times 10^{-7}}$$ Stress in lower wire $$= \frac{(10 + m)g}{0.004 \, \mathrm{cm}^2}$$ $$= \frac{(10 + m) \times 10}{4 \times 10^{-7}}$$ Upper wire breaks: $$\frac{(40 + m) \times 10}{8 \times 10^{-7}} = 12 \times 10^8$$ So, maximum mass, without breaking any wire is 38 kg.

Question 44

Physics · Alternating Current · Single correct

An a.c. source of angular frequency $\omega$ is connected across a resistor $R$ and a capacitor $C$ in series. The current is observed as $I$. Now the frequency of the source is changed to $\omega/4$, (keeping the voltage unchanged) the current is found to be $I/3$. The ratio of resistance to reactance at frequency $\omega$ is

  1. $\sqrt{\frac{6}{7}}$
  2. $\sqrt{\frac{3}{5}}$
  3. $\sqrt{\frac{7}{8}}$
  4. $\sqrt{\frac{3}{4}}$

Answer: (c)

Solution

As we know that current in RLC circuit is given by $$I = \frac{V}{Z} = \frac{V}{\left[R^2 + (X_L - X_C)^2\right]^{1/2}}$$ $$I = \frac{V_0}{\sqrt{R^2 + \left(\omega L - \frac{1}{\omega C}\right)^2}}$$ As circuit is RC $$I_0 = \frac{V_0}{(R^2 + X_C^2)^{1/2}}$$ $$\frac{I_0}{3} = \frac{V_0}{\left[R^2 + (4X_C)^2\right]^{1/2}}$$ $$R^2 + (X_C)^2 = \frac{(R^2 + 16X_C^2)}{9}$$ $$\frac{8R^2}{9} = \frac{7X_C^2}{9}$$ $$\frac{R}{X_C} = \sqrt{\frac{7}{8}}$$

Question 45

Physics · Semiconductor Electronics: Materials, Devices and Simple Circuits · Single correct

For the given logic circuit, which of the following inputs combination will make both LED-1 and LED-2 to glow ?

  1. A = 0, B = 1, C = 1
  2. A = 1, B = 0, C = 0
  3. A = 1, B = 0, C = 1
  4. A = 1, B = 1, C = 0

Answer: (c)

Solution

The circuit consists of an OR gate and two AND gates. The inputs to the OR gate are 1 (A) and 0 (B), resulting in an output of 1. This output is fed into the first AND gate along with another input of 1, resulting in an output of 1. This output is connected to LED-1, which remains off (0). The output of the first AND gate is also fed into the second AND gate along with input 1 (C), resulting in an output of 1. This output is connected to LED-2, which also remains off (0).

Question 46

Physics · Mechanical Properties of Solids · Numerical

A cube has side length $5\,\mathrm{\, cm}$ and modulus of rigidity 10^5 $\mathrm{\, N/m^2}$. The displacement produced by a force of $10\,\mathrm{\, N}$ in the upper face of cube is $\ldots$ mm.

Answer: 2

Solution

The equation for viscosity is given by $$\eta = \frac{F/A}{\phi} = \frac{Fh}{Ax}.$$ Solving for $x$, we have $$x = \frac{Fh}{A\eta} = \frac{10 \times 5 \times 10^{-2}}{25 \times 10^{-4} \times 10^5} = \frac{1}{500} \, \mathrm{m}.$$ Therefore, $x = 2 \, \mathrm{mm}$.

Question 47

Physics · Motion in a Straight Line · Numerical

From $18\,\mathrm{m}$ height above the ground a ball is dropped from rest. The height above the ground at which the magnitude of velocity equal to the magnitude of acceleration (in the same set of units) due to gravity is $\ldots \mathrm{m}$. (Take $g = 10 \, \mathrm{m/s^2}$ and neglect the air resistance)

Answer: 13

Solution

At any time $t$ after it is released, velocity $V = gt$. Acceleration of the ball remains constant $= g$. Therefore, both will be equal at $t = 1 \, sec$. Thus, the position of the ball from the ground will be $(18 - 5) \, m$.

Question 48

Physics · Waves · Numerical

A transverse wave on a string is described by $y = 3 \sin (36t + 0.018x + \pi/4)$. Where $x$, $y$ are in cm and $t$ in seconds. The least distance between the two successive crests in the wave is $\ldots$ cm. (Nearest integer) $(\pi = 3.14)$

Answer: 349

Solution

Least distance between successive crest = $\lambda$ $y = A \sin(\omega t + kx + \phi)$, $\omega = 2 \pi f$ and $k = \frac{2\pi}{\lambda}$ & $y = A \sin(36t + 0.018x + \pi/4)$ $\Rightarrow k = 0.018 \, \mathrm{cm}^{-1} \Rightarrow \frac{2\pi}{\lambda} = 0.018$ $$\lambda = \frac{2\pi}{0.018} = \frac{2 \times 3.14}{18 \times 10^{-3}} \, \mathrm{cm} = 348.88 \, \mathrm{cm}$$ $\approx 349 \, \mathrm{cm}$ (nearest integer)

Question 49

Physics · Moving Charges and Magnetism · Numerical

The charged particle moving in a uniform magnetic field of $\left(3\hat{i} + 2\hat{j}\right) \, \mathrm{T}$ has an acceleration $\left(4\hat{i} - \frac{x}{2}\hat{j}\right) \, \mathrm{m/s^2}$. The value of $x$ is

Answer: 12

Solution

The force $\vec{F}_B$ is proportional to $(\vec{V} \times \vec{B})$. This implies $\vec{F}_B \perp \vec{B}$. Given $\vec{a} \perp \vec{B}$, it follows that $\vec{a} \cdot \vec{B} = 0$. Solving $12 - x = 0$ gives $x = 12$.

Question 50

Physics · Electromagnetic Induction · Numerical

In the given circuit below inductance values of $L_1$, $L_2$ and $L_3$ are same. The magnetic energy stored in the entire circuit is $(U_t)$ and that stored in the $L_2$ inductor is $(U_l)$. $(U_t/U_l)$ is $\ldots$. (Ignore the mutual inductance if any)

Answer: 6

Solution

Magnetic energy of inductor is $U = \frac{1}{2} LI^2$. So $U_t = \frac{1}{2} LI^2 + \frac{1}{2} L \left( \frac{I}{2} \right)^2 + \frac{1}{2} L \left( \frac{I}{2} \right)^2 = \frac{3}{4} LI^2$. $$U_\ell = \frac{1}{2} L \left( \frac{I}{2} \right)^2 \Rightarrow \frac{U_t}{U_\ell} = 6$$

Chemistry

Question 51

Chemistry · Some Basic Concepts of Chemistry · Single correct

How many grams of residue is obtained by heating $2.76\,\mathrm{g}$ of silver carbonate ? $\newline$ (Given : Molar mass of C, O and Ag are 12, 16 and $108\,\mathrm{g \, mol^{-1}}$ respectively)

  1. $1.08\,\mathrm{g}$
  2. $2.16\,\mathrm{g}$
  3. $3.24\,\mathrm{g}$
  4. $4.32\,\mathrm{g}$

Answer: (b)

Solution

The reaction is given by: $$\mathrm{Ag_2CO_3(s)} \xrightarrow{\Delta} 2\mathrm{Ag(s)} + \mathrm{CO_2(g)} + \frac{1}{2}\mathrm{O_2(g)}$$ Given $2.76 \, \mathrm{g}$ of $\mathrm{Ag_2CO_3}$: $$\frac{1}{100} \, \mathrm{mol}$$ Moles of $\mathrm{Ag(s)} = \frac{2}{100} \, \mathrm{mol}$ Mass of residue $= 2.16 \, \mathrm{g}$

Question 52

Chemistry · Structure of Atom · Single correct

Arrange the following atomic orbitals of multi electron atoms in order of increasing energy. (A) n = 3, $\ell$ = 2, m = +1 (B) n = 4, $\ell$ = 0, m = 0 (C) n = 6, $\ell$ = 1, m = 0 (D) n = 5, $\ell$ = 1, m = +1 (E) n = 2, $\ell$ = 1, m = +1

  1. C < D < B < A < E
  2. B < A < E < C < D
  3. E < C < D < B < A
  4. E < B < A < D < C

Answer: (d)

Solution

(A) $n = 3$, $l = 2$, $m = +1$; $(n + l) = 5$ (B) $n = 4$, $l = 0$, $m = 0$; $(n + l) = 4$ (C) $n = 6$, $l = 1$, $m = 0$; $(n + l) = 7$ (D) $n = 5$, $l = 1$, $m = +1$; $(n + l) = 6$ (E) $n = 2$, $l = 1$, $m = +1$; $(n + l) = 3$ More the value of $(n + l)$, more will be the energy of that particular orbital. Ans. E < B < A < D < C

Question 53

Chemistry · Structure of Atom · Single correct

Identify the correct statements from the following: A. Heisenberg uncertainty principle is applicable to electron. B. The size of $2p_x$ orbital is less than the size of $3p_x$ orbital. C. The energy of $2s$ orbital of H atom is equal to the energy of $2s$ orbital of Li. D. The electronic configuration of Cr is $[\mathrm{Ar}] \, 3d^5 4s^1$ Choose the correct answer from the options given below:

  1. A, B and C only
  2. A, B and D only
  3. B, C, and D only
  4. A, C and D only

Answer: (b)

Question 54

Chemistry · Solutions · Single correct

What is the mole fraction of water in 10$\%$ by weight (w/w) of aqueous urea solution? [Given: Molar mass of H, O, C and N are 1, 16, 12 and $14\,\mathrm{g \, mol^{-1}}$ respectively]

  1. 0.825
  2. 0.032
  3. 0.867
  4. 0.967

Answer: (d)

Solution

Mass ratio = mol ratio $\times$ GMM ratio $$\frac{10}{90} = \frac{n}{N} \times \frac{60}{18}$$ $$\frac{n}{N} = \frac{1}{30}$$ $$x_{\mathrm{H_2O}} = \frac{W}{n+N} = \frac{30}{31} = 0.967$$

Question 55

Chemistry · Equilibrium · Single correct

$M_3A_2$ is a sparingly soluble salt of molar mass $y \, \mathrm{g \, mol^{-1}}$ and solubility $x \, \mathrm{g \, L^{-1}}$. The ratio of the molar concentration of the anion $(A^{3-})$ to the solubility product of the salt is

  1. $\frac{1}{54} \cdot \frac{y^4}{x^4}$
  2. $\frac{y^5}{108x^4}$
  3. $108 \cdot \frac{x^5}{y^5}$
  4. $\frac{1}{108} \cdot \frac{y^4}{x^4}$

Answer: (a)

Solution

The reaction is given by: $$\mathrm{M_3A_2 (s) \rightleftharpoons 3M^{+2} (aq.) + 2A^{-3} (aq.)}$$ Molarity is given as: $$\frac{x}{y} - - 3 \frac{x}{y} 2 \frac{x}{y}$$ The solubility product is: $$K_{sp} = [\mathrm{M^{+2}}]^3 [\mathrm{A^{-3}}]^2$$ Substituting the molarity values: $$K_{sp} = \left[\frac{3x}{y}\right]^3 \left[\frac{2x}{y}\right]^2$$ The ratio of $\frac{[\mathrm{A^{-3}}]}{K_{sp}}$ is: $$\frac{2x/y}{\left[\frac{3x}{y}\right]^3 \left[\frac{2x}{y}\right]^2}$$ Simplifying gives: $$= \frac{1}{54} \frac{y^4}{x^4}$$

Question 56

Chemistry · Equilibrium · Single correct

Arrange the following resultant mixtures in increasing order of their pH values A. 10 mL 0.2 M Ca(OH)$_2$ + 25 mL 0.1 M HCl B. 10 mL 0.01 M H$_2$SO$_4$ + 10 mL 0.01 M Ca(OH)$_2$ C. 10 mL 0.1 M H$_2$SO$_4$ + 10 mL 0.1 M KOH Choose the correct answer from the options given below :

  1. B < C < A
  2. C < A < B
  3. C < B < A
  4. A < C < B

Answer: (c)

Solution

(A) $\mathrm{H^+_{(aq)}} + \mathrm{OH^-_{(aq)}} \rightarrow \mathrm{H_2O(\ell)}$ At $t = 0$, $2.5 \, \mathrm{mmol}$ of $\mathrm{H^+}$ and $4 \, \mathrm{mmol}$ of $\mathrm{OH^-}$. At $t = \infty$, $0 \, \mathrm{mmol}$ of $\mathrm{H^+}$ and $1.5 \, \mathrm{mmol}$ of $\mathrm{OH^-}$. In the final solution, $[\mathrm{OH^-}] = \frac{1.5 \, \mathrm{mmol}}{35 \, \mathrm{ml}} = \frac{1.5}{35}$. pOH $= -\log \frac{1.5}{35}$. pH $= 14 + \log \left( \frac{1.5}{35} \right)$. (B) $\mathrm{H^+_{(aq)}} + \mathrm{OH^-_{(aq)}} \rightarrow \mathrm{H_2O(\ell)}$ At $t = 0$, $0.2 \, \mathrm{mmol}$ of $\mathrm{H^+}$ and $0.2 \, \mathrm{mmol}$ of $\mathrm{OH^-}$. Final pH $= 7$. (C) $\mathrm{H^+_{(aq)}} + \mathrm{OH^-_{(aq)}} \rightarrow \mathrm{H_2O(\ell)}$ At $t = 0$, $2 \, \mathrm{mmol}$ of $\mathrm{H^+}$ and $1 \, \mathrm{mmol}$ of $\mathrm{OH^-}$. At $t = \infty$, $1 \, \mathrm{mmol}$ of $\mathrm{H^+}$ and $0 \, \mathrm{mmol}$ of $\mathrm{OH^-}$. Final pH $< 7$. So, order of pH values: (C) < (B) < (A)

Question 57

Chemistry · Chemical Kinetics and Nuclear Chemistry · Single correct

First order gas phase reaction $\mathrm{A\rightarrow B+C}$ $p_i=$ initial pressure of gas A, $p_t=$ total pressure of the reaction mixture at time $t$ Expression of rate constant $(k)$ is

  1. $\frac{1}{t} \ln \frac{p_i}{2p_i - p_t}$
  2. $\frac{1}{t} \ln \frac{2p_i}{p_i - p_t}$
  3. $\frac{1}{t} \ln \frac{p_i}{3p_i - 2p_t}$
  4. $\frac{1}{t} \ln \frac{3p_i}{4p_i - p_t}$

Answer: (a)

Solution

The reaction is given as A(g) $\rightarrow$ B(g) + C(g). At time $t = 0$, the pressure is $P_i$ for A, and $-$ for B and C. At time $t = t$, the pressure is $P_i - x$ for A, $x$ for B, and $x$ for C. As given, $(P_i - x) + x + x = P_t$. Therefore, $x = (P_t - P_i)$. The rate constant $K$ is given by: $$K = -\frac{1}{t} \ln \frac{P_i}{P_i - x} = -\frac{1}{t} \ln \frac{P_i}{P_i - (P_t - P_i)}$$ Simplifying, we get: $$K = \frac{1}{t} \ln \frac{P_i}{2P_i - P_t}$$

Question 58

Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct

Statement I: The correct order of electronegativity of fluorine, oxygen nitrogen is $\mathrm{F} > \mathrm{O} > \mathrm{N}$. Statement II: The oxidation state of oxygen in $\mathrm{OF}_2$ is $+2$ and in $\mathrm{Na}_2\mathrm{O}$ is $-2$. In the light of the above statements, choose the correct answer from the options given below

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true

Answer: (a)

Solution

Statement-I $$(\mathrm{EN})_F = 4.0$$ $$(\mathrm{EN})_O = 3.5$$ on pauling scale $$(\mathrm{EN})_N = 3.0$$ $$(\mathrm{EN})_F > (\mathrm{EN})_O > (\mathrm{EN})_N$$ Statement-II Oxidation state of oxygen in $\mathrm{OF_2}$ $$\mathrm{OF_2} \Rightarrow x - 1 \times 2 = 0$$ $$x = +2$$ Oxidation state of oxygen in $\mathrm{Na_2O}$ $$\mathrm{Na_2O} \Rightarrow +1 \times 2 + x = 0$$ $$x = -2$$ Both the statement I and statement II are correct.

Question 59

Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct

Correct statements from the following are: A. Nitrogen in oxidation states from $+1$ to $+4$ disproportionates in acid medium. B. Nitrogen has the ability of form $d\pi-p\pi$ multiple bonds with itself and other elements with small size and high electronegativity. C. N-N single bond is stronger than P-P single bond. D. Nitrogen has highest density in its group due to small size. E. The maximum covalency of nitrogen is four since it has only four valence orbitals for bonding. Choose the correct answer from the options given below:

  1. B, C, and D only
  2. C, D, and E only
  3. A, C and E only
  4. A and E only

Answer: (d)

Solution

(A) In the case of nitrogen, all oxidation states from $+1$ to $+4$ tend to disproportionate in acid solution. For example. $$3\mathrm{HNO_2} \rightarrow \mathrm{HNO_3} + \mathrm{H_2O} + 2\mathrm{NO}$$ (B) Nitrogen form $p_\pi - p_\pi$ bonds with itself and other elements with small size and high electronegativity, $d_\pi - p_\pi$ is not possible with itself as it has no d-orbital. (C) The single N-N bond is weaker than the single P–P bond because of high interelectronic repulsion of the non-bonding electrons (lone pair), owing to the small bond length. (D) Nitrogen has lowest density in its group. (E) The maximum covalency of nitrogen is four. Correct answer are (A) and (E)

Question 60

Chemistry · The Solid State · Single correct

Which of the following is NOT a physical or chemical characteristics of interstitial compounds?

  1. They have high melting points, higher than those of pure metals
  2. They are very soft ionic in nature
  3. They retain metallic conductivity
  4. They are chemically inert and usually non-stoichiometric

Answer: (b)

Solution

The physical and chemical characteristics of interstitial compounds are: (1) They have high melting points, higher than those of pure metals. (2) They are very hard, some borides approach diamond in hardness. (3) They retain metallic conductivity. (4) They are chemically inert and usually non-stoichiometric. Ans. (2)

Question 61

Chemistry · Co-ordination Compounds · Single correct

The correct statements about metal carbonyls are A. The metal-carbon bonds in metals carbonyls possess both $\sigma$ and $\pi$-character. B. Due to synergic bonding interactions between metals and CO ligand the metal-carbon bond becomes weak. C. The metal-carbon $\sigma$ bond is formed by the donation of lone pair of electrons on the carbonyl carbon into a vacant orbital of metal. D. The metal-carbon $\pi$ bond is formed by the donation of electrons from filled d-orbital of metal into vacant $\pi^*$ orbital of CO. Choose the correct answer from the options given below:

  1. A and B only
  2. A, C and D only
  3. B and C only
  4. A and D only

Answer: (b)

Solution

(A) The metal-carbon bonds in metal carbonyls possess both $\sigma$ and $\pi$-character. (B) The metal to ligand bonding creates a synergic effect which strengthens the bond between CO and the metal i.e. metal carbon bond becomes strong. (C) The metal-carbon $\sigma$ is formed by the donation of lone pair of electrons on the carbonyl carbon into a vacant orbital of metal. (D) The metal-carbon $\pi$ bond is formed by the donation of electrons from filled d-orbital of metal into vacant $\pi^*$ orbital of CO. Correct answer are A, C, D

Question 62

Chemistry · Co-ordination Compounds · Single correct

Given below are two statements : Statement I : Each electron in $e_g$ orbitals destabilizes the orbitals by $+0.6 \, \Delta_0$ and each electron in the $t_{2g}$ orbitals stabilizes the orbitals by $-0.4 \, \Delta_0$ in an octahedral field on the basis of crystal field theory. Statement II : All the d-orbitals of the transition metals have the same energy in their free atomic state but when a complex is formed the ligands destroy the degeneracy of these orbitals on the basis of crystal field theory. In the light of the above statements, choose the correct answer from the options given below.

  1. Both Statement I and Statement II are correct
  2. Both Statement I and Statement II are incorrect
  3. Statement I is correct but Statement II is incorrect
  4. Statement I is incorrect but Statement II is correct

Answer: (a)

Solution

Statement-I: In the absence of ligands, the isolated 'd' subshell is shown. In the presence of ligands, the energy levels split into $e_x$ and $t_{2g}$ with $+0.6\Delta_0$ and $-0.4\Delta_0$ respectively. Statement-II: The degeneracy of the d-orbitals is removed due to ligand electron-metal electron repulsions according to crystal field theory. Both the statement I and II are correct.

Question 63

Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct

Given below are two statements: Statement I: On the basis of inductive effect, the order of stability of alkyl carbanions is $\mathrm{CH}_3^- > \mathrm{CH}_3 - \mathrm{CH}_2^- > (\mathrm{CH}_3)_2\mathrm{CH} > (\mathrm{CH}_3)_3\mathrm{C}^-.$ Statement II: Allyl and benzyl carbanions are more stabilised by inductive effect and not by resonance effect. In the light of the above statements choose the correct answer from the options given below

  1. Both Statement I and Statement II are correct
  2. Both Statement I and Statement II are incorrect
  3. Statement I is correct and Statement II is incorrect
  4. Statement I is incorrect and Statement II is correct

Answer: (c)

Solution

Statement-I $\Theta \mathrm{CH_3} > \mathrm{CH_3} - \Theta \mathrm{CH_2} > (\mathrm{CH_3})_2 \Theta \mathrm{CH} > (\mathrm{CH_3})_3 \Theta \mathrm{C}$ It is correct order of anion stability and it is based on inductive effect. Statement-II $\mathrm{CH_2 = CH - \Theta CH_2}$ Allyl anion $\&$ Benzyl carbanion Both are stabilised by resonance. Statement-I : Correct Statement-II : Incorrect

Question 64

Chemistry · Hydrocarbons · Single correct

"P" is hydrocarbon of molecular formula : $\mathrm{C}_8\mathrm{H}_{14}$. On ozonolysis, "P" forms "Q". "Q" on treatment with alkali under reflux condition produces "R", which on treatment with $\mathrm{I}_2/\mathrm{NaOH}$ gives a yellow precipitate. Acidification of the solution gives "S". The structure of "S" given below: The correct structure of "P" is

Answer: (d)

Solution

The reaction sequence begins with ozonolysis of the alkene using $\mathrm{O_3}$ and $\mathrm{Zn/H_2O}$, resulting in the formation of a diketone. This diketone undergoes an aldol condensation in the presence of $\mathrm{OH^-}$ and heat ($\Delta$), forming a cyclic compound. The cyclic compound is then treated with $\mathrm{NaOH}$ and $\mathrm{I_2}$, leading to the formation of a carboxylate ion and $\mathrm{CHI_3}$ as products.

Question 65

Chemistry · Hydrocarbons · Multiple correct

For the following Friedel Craft's alkylation reaction, which of the statements are correct? Choose the correct answer from the options given below:

  1. A and D only
  2. B and C only
  3. A and C only
  4. B and D only

Answer: (b)

Solution

The reaction begins with the alkyl chloride reacting with $AlCl_3$ to form a carbocation. This carbocation then undergoes a rearrangement to form a more stable carbocation. The benzene ring attacks this carbocation, leading to the formation of the major product, which is an alkylated benzene.

Question 66

Chemistry · Amines · Single correct

Benzyl isocyanide can be obtained from

  1. A and B only
  2. A and C only
  3. B and D only
  4. D and E only

Answer: (a)

Solution

(A) Benzyl bromide reacts with $\mathrm{AgCN}$ to form benzyl isocyanide. (B) Benzylamine reacts with $\mathrm{CHCl_3}$ and aqueous $\mathrm{NaOH}$ to form benzyl isocyanide. (C) Benzyl bromide with $\mathrm{AgCN}$ gives no reaction. (D) Benzylamine reacts with $\mathrm{CHCl_3}$ and aqueous $\mathrm{NaOH}$ to form benzyl isocyanide. (E) Benzyl bromide reacts with $\mathrm{KCN}$ to form benzyl cyanide. (A) and (B) give the correct product.

Question 67

Chemistry · Alcohols, Phenols and Ethers · Single correct

Consider compounds A, B and C with following structural formulae A = $\mathrm{CH_3 - CH_2 - CH_2 - CH_2 - CH_2 - OH}$ B = $\mathrm{CH_2 = CH - CH_2 - CH_2 - CH_3}$ C = $\mathrm{HO - CH_2 - CH_2 - CH(OH) - CH_3}$ For the conversion of B from A, reagent (D) required is $\ldots$ and structural formula of product (E) obtained when C undergoes same reaction using excess reagent (D) is $\ldots$

Answer: (d)

Solution

The reaction of compound (A) with concentrated $\mathrm{H_2SO_4}$ or $\mathrm{H_3PO_4}$ leads to the formation of compound (B). Similarly, compound (C) reacts with concentrated $\mathrm{H_2SO_4}$ or $\mathrm{H_3PO_4}$ in excess to form compound (E).

Question 68

Chemistry · Amines · Single correct

Identify the incorrect statements:

  1. A and D only
  2. A and C only
  3. B and C only
  4. A and B only

Answer: (c)

Solution

(A) Basic strength order: $C_6H_5CH_2NH_2 > C_6H_5NH_2$. (B) Cannot be synthesized by Gabriel phthalimide synthesis. (C) Hoffmann's bromamide reaction: $C_6H_5CONH_2 \xrightarrow{Br_2 + NaOH} C_6H_5CH_2NH_2$ (Aliphatic amine). (D) Reaction: $C_6H_4NO_2NH_2 \xrightarrow{NaNO_2 + HCl, \, 0^\circ C} C_6H_4NO_2N_2Cl \xrightarrow{\Delta, \, H_2O} C_6H_4NO_2OH$ (Soluble in NaOH). Only (B) and (C) are incorrect hence Ans. is (3).

Question 69

Chemistry · Biomolecules · Single correct

Identify the correct statements A. Glucose exist in two anomeric forms. B. Anomers of glucose differ in configuration at C-1 in cyclic hemiacetal structure. C. Melting point of $\alpha$-anomer of glucose is greater than $\beta$-anomer. D. Specific rotation of $\alpha$-anomer is $+19^\circ$ while for $\beta$-anomer is $+112^\circ$ E. $\alpha$ and $\beta$-anomers of glucose are prepared by crystallization of saturated glucose solution at $303 \, \mathrm{K}$ and $371 \, \mathrm{K}$ respectively. Choose the correct answer from the options given below:

  1. A and B only
  2. B and C only
  3. A, B and D only
  4. A, B and E only

Answer: (d)

Solution

It is based on theory

Question 70

Chemistry · Analytical Chemistry · Single correct

Statement I: Sodium dichromate and potassium dichromate are classified as primary standard in titrimetric analysis. Statement II: Phenolphthalein is a weak base, therefore it dissociates in acidic medium. In the light of the above statements, choose the correct answer from the options given below

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true

Answer: (b)

Solution

Na_2Cr_2O_7 is hygroscopic in nature and is not used as a primary standard. Phenolphthalein is a weak acid.

Question 71

Chemistry · Chemical Bonding and Molecular Structure · Numerical

Consider the following species $\mathrm{BrF_5,XeF_5^-,BF_4^-,ICl_4^-,XeF_4,SF_4,NH_4^+,ClF_3,XeF_2,ICl_2^-}$ Number of species having $sp^3d$ hybridized central atom is $\underline{\hspace{1cm}}$

Answer: 4

Solution

The species and their hybridisation are as follows: 1. $\mathrm{BrF_5}$: $\mathrm{sp^3d^2}$ 2. $\mathrm{XeF_5^-}$: $\mathrm{sp^3d^3}$ 3. $\mathrm{BF_4^-}$: $\mathrm{sp^3}$ 4. $\mathrm{ICl_4^-}$: $\mathrm{sp^3d^2}$ 5. $\mathrm{XeF_4}$: $\mathrm{sp^3d^2}$ 6. $\mathrm{SF_4}$: $\mathrm{sp^3d}$ 7. $\mathrm{NH_4^+}$: $\mathrm{sp^3}$ 8. $\mathrm{ClF_3}$: $\mathrm{sp^3d}$ 9. $\mathrm{XeF_2}$: $\mathrm{sp^3d}$ 10. $\mathrm{ICl_2^-}$: $\mathrm{sp^3d}$ Number of species having $\mathrm{sp^3d}$ hybridisation are 4.

Question 72

Chemistry · Analytical Chemistry · Numerical

In an estimation of sulphur by Carius method 0.2 g of the substance gave 0.6 g of $\mathrm{BaSO}_4$. The percentage of sulphur in the substance is $\ldots$%. (Given molar mass in g mol$^{-1}$ S : 32, $\mathrm{BaSO}_4$ : 231)

Answer: 42

Solution

Moles of $\mathrm{BaSO_4}$ formed $\frac{0.6 \, \mathrm{gm}}{231 \, \mathrm{gm}} = 0.0026$. Moles of $\mathrm{BaSO_4} = Moles of S$. Mass of sulphur $(W_s) = \frac{0.6}{231} \times 32$. Percentage of sulphur $(S) = \frac{0.6 \times 32}{231 \times 0.2} \times 100$. $$= \frac{1920}{46.2} = 41.558 \approx 42$$

Question 73

Chemistry · Alcohols, Phenols and Ethers · Numerical

One mole of phenol is treated with dilute $\mathrm{HNO}_3$ at $298\,\mathrm{K}$ to give a mixture of products. The mixture is separated by steam distillation. The seam volatile compound $(X)$ is separated. The increase in percentage of oxygen in $(X)$ with respect to phenol is $\ldots 10^{-10}\%$ (Given molar mass in $\mathrm{g\,mol^{-1}} \mathrm{H:1}$, $\mathrm{C:12}$, $\mathrm{N:14}$, $\mathrm{O:16}$)

Answer: 175

Solution

% oxygen in phenol = $\frac{16}{94} \times$ 100 = 17.02$\%$ % oxygen in o-Nitrophenol ($C_6H_5NO_3$) Molecular mass = $C_6H_5NO_3 = 139 \, \mathrm{g/m}$ $$= \frac{48}{139} \times 100 = 34.53\%$$ % increase = (34.53 - 17.02) = 17.5 $$17.5 \times 10^{-1} = 175 Answer$$

Question 74

Chemistry · Equilibrium · Numerical

The values of pressure equilibrium constant recorded at different temperatures for the following equilibrium reaction have been given below: A(g) $\rightleftharpoons$ B(g) + C(g) The magnitude of $\frac{\Delta H^\circ}{R}$ calculated from the above data is $\ldots$ (Nearest integer)

Answer: 230

Solution

Using formula $$\log K_{P_2} - \log K_{P_1} = \frac{\Delta H}{2.303 R} \left( \frac{1}{T_1} - \frac{1}{T_2} \right)$$ $$3.5 - 2.5 = \frac{\Delta H}{2.303 R} (0.06 - 0.05)$$ $$\frac{\Delta H}{R} = \frac{2.303}{0.01}$$ $$\frac{\Delta H}{R} = 230.3 \approx 230$$

Question 75

Chemistry · Chemical Kinetics and Nuclear Chemistry · Numerical

If the half life of a first order reaction is 6.93 minutes then the time required for completion of 99$\%$ of the reaction will be $\ldots$ minutes. (Given: $\log 2 = 0.3010$)

Answer: 46

Solution

Given $t_{1/2} = \frac{\ln 2}{K} \implies K_1 = \frac{0.693}{6.93} \implies 0.1 \, min^{-1}$. $t_{99\%} = \frac{1}{K} \ln \left[ \frac{A_0}{A_t} \right]$ $$= \frac{1}{0.1} \ln \left[ \frac{100}{1} \right] \implies \frac{2 \ln 10}{0.1}$$ $$= \frac{2 \times 2.303}{0.1}$$ $$\implies 46.06 \, min \approx 46$$