JEE Main 29 January 2025 Shift 1 question paper with solutions
JEE Main 29 January 2025 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 · Conic Sections · Single correct
Let the line $x + y = 1$ meet the circle $x^2 + y^2 = 4$ at the points $A$ and $B$. If the line perpendicular to $AB$ and passing through the mid point of the chord $AB$ intersects the circle at $C$ and $D$, then the area of the quadrilateral $ADBC$ is equal to:
14
37
214
57
Answer: (c)
Solution
By solving $x = y$ with the circle, we get $C(\sqrt{2}, \sqrt{2})$ and $D(-\sqrt{2}, -\sqrt{2})$. By solving $x + y = 1$ with the circle $x^2 + y^2 = 4$, we set $$A \left( \frac{1 + \sqrt{7}}{2}, \frac{1 - \sqrt{7}}{2} \right)$$ & $$B \left( \frac{1 - \sqrt{7}}{2}, \frac{1 + \sqrt{7}}{2} \right)$$ Therefore, the area of quadrilateral $ACBD$ is $$= 2 \times Area of \triangle BCD$$ $$= 2 \times \frac{1}{2} \begin{vmatrix} \sqrt{2} & \sqrt{2} & 1 \\ \frac{1 - \sqrt{7}}{2} & \frac{1 + \sqrt{7}}{2} & 1 \\ -\sqrt{2} & -\sqrt{2} & 1 \end{vmatrix}$$ $$= 2\sqrt{14}$$
Question 2
Maths · Determinants · Single correct
Let M and m respectively be the maximum and the minimum values of $$f(x) = \begin{vmatrix} 1 + \sin^2 x & \cos^2 x & 4 \sin 4x \\ \sin^2 x & 1 + \cos^2 x & 4 \sin 4x \\ \sin^2 x & \cos^2 x & 1 + 4 \sin 4x \end{vmatrix}, \ x \in \mathbb{R}$$ Then $M^4 - m^4$ is equal to:
1280
1295
1215
1040
Answer: (a)
Solution
Given the matrix: $$\begin{vmatrix} 1 + \sin^2 x & \cos^2 x & 4 \sin 4x \\ \sin^2 x & 1 + \cos^2 x & 4 \sin 4x \\ \sin^2 x & \cos^2 x & 1 + 4 \sin 4x \end{vmatrix}, x \in \mathbb{R}$$ Perform the row operations: $$R_2 \to R_2 - R_1 \& R_3 \to R_3 - R_1$$ The matrix becomes: $$\begin{vmatrix} 1 + \sin^2 x & \cos^2 x & 4 \sin 4x \\ -1 & 1 & 0 \\ -1 & 0 & 1 \end{vmatrix}$$ Expand about $R_1$, we get $$f(x) = 2 + 4 \sin 4x$$ Thus, $M = max value of f(x) = 6$ $M = min value of f(x) = -2$ Therefore, $M^4 - M^4 = 1280$
Question 3
Maths · Conic Sections · Single correct
Two parabolas have the same focus $(4, 3)$ and their directrices are the $x$-axis and the $y$-axis, respectively. If these parabolas intersects at the points $A$ and $B$, then $(AB)^2$ is equal to:
392
384
192
96
Answer: (c)
Solution
The parabolas are $$(x - 4)^2 + (y - 3)^2 = x^2 \ldots (i)$$ and $$(x - 4)^2 + (y - 3)^2 = y^2 \ldots$$ If point of intersection are $A(x_1, y_1)$ and $B(x_2, y_2)$. By solving (i) and (ii), we get $$x_1 + x_2 = 14 and x_1 x_2 = 25$$ $$(AB)^2 = 2 \left( (x_1 + x_2)^2 - 4x_1 x_2 \right) = 192$$
Question 4
Maths · Straight Lines and Pair of Straight Lines · Single correct
Let $ABC$ be a triangle formed by the lines $7x - 6y + 3 = 0$, $x + 2y - 31 = 0$ and $9x - 2y - 19 = 0$. Let the point $(h, k)$ be the image of the centroid of $\triangle ABC$ in the line $3x + 6y - 53 = 0$. Then $h^2 + k^2 + hk$ is equal to:
47
37
36
40
Answer: (b)
Solution
$\therefore$ centroid of $\triangle ABC =\left(\dfrac{9+3+5}{3},\dfrac{11+4+13}{3}\right) =\left(\dfrac{17}{3},\dfrac{28}{3}\right)$ Let image of centroid with respect to line mirror is $(h,k)$ $\therefore\; \left(\dfrac{k-\frac{28}{3}}{h-\frac{17}{3}}\right) \left(-\dfrac12\right) =-1 \qquad\cdots(1)$ $\left(\dfrac{h+\frac{17}{3}}{2}\right) + 6\left(\dfrac{k+\frac{28}{3}}{2}\right) =53 \qquad\cdots(2)$ Solving (1) \& (2) we get $h=3,\quad k=4$ $\therefore\;h^2+k^2+hk=37$
Question 5
Maths · Vector Algebra · Single correct
Let $\vec{a}=2\hat{i}-\hat{j}+3\hat{k}$, $\vec{b}=3\hat{i}-5\hat{j}+\hat{k}$ and $\vec{c}$ be a vector such that $\vec{a}\times\vec{c}=\vec{c}\times\vec{b}$ and $(\vec{a}+\vec{c})\cdot(\vec{b}+\vec{c})=168$. Then the maximum value of $|\vec{c}|^2$ is:
462
77
154
308
Answer: (d)
Solution
Given $\vec{a} = 2\hat{i} - \hat{j} + 3\hat{k}$ and $\vec{b} = 3\hat{i} - 5\hat{j} + 3\hat{k}$. We have $\vec{a} \times \vec{c} = \vec{c} \times \vec{b}$. Therefore, $\vec{a} \times \vec{c} + \vec{b} \times \vec{c} = 0$. This implies $(\vec{a} + \vec{b}) \times \vec{c} = 0$. Thus, $\vec{c} = \lambda(\vec{a} + \vec{b})$. So, $\vec{c} = \lambda(5\hat{i} - 6\hat{j} + 4\hat{k}) \ldots (1)$. The magnitude squared is $|\vec{c}|^2 = \lambda^2(25 + 36 + 16)$. Therefore, $|\vec{c}|^2 = 77\lambda^2$. The expression $(\vec{a} + \vec{c}) \cdot (\vec{b} + \vec{c}) = 168$ gives $\vec{a} \cdot \vec{b} + \vec{a} \cdot \vec{c} + \vec{c} \cdot \vec{b} + |\vec{c}|^2 = 168$. Simplifying, $14 + \vec{c} \cdot (\vec{a} + \vec{b}) + 77\lambda^2 = 168$. Using equation (1), $\lambda|5\hat{i} - 6\hat{j} + 4\hat{k}|^2 + 77\lambda^2 = 154$. This simplifies to $77\lambda + 77\lambda^2 - 154 = 0$. Solving $\lambda^2 + \lambda - 2 = 0$, we find $\lambda = -2, 1$. Therefore, the maximum value of $|\vec{c}|^2$ occurs when $\lambda = -2$. Thus, $|\vec{c}|^2 = 77\lambda^2 = 77 \times 4 = 308$.
Question 6
Maths · Permutations and Combinations · Single correct
Let P be the set of seven digit numbers with sum of their digits equal to 11. If the numbers in P are formed by using the digits 1, 2 and 3 only, then the number of elements in the set $P$ is:
173
164
158
161
Answer: (d)
Solution
(i) number of numbers created using 1111133 = $\($ $\frac{7!}{5!2!}$ $\Rightarrow$ 21 $\)$ (ii) number of numbers created using 1111223 = $\($ $\frac{7!}{4!2!}$ $\Rightarrow$ 105 $\)$ (iii) number of numbers created using 1112222 = $\($ $\frac{7!}{4!3!}$ $\Rightarrow$ 35 $\)$ Total = 161
Question 7
Maths · Applications of Integrals · Single correct
Let the area of the region \[ \left\{ (x,y): 2y\le x^2+3,\; y+|x|\le3,\; y\ge|x-1| \right\} \] be $A$. Then $6A$ is equal to:
16
12
14
18
Answer: (c)
Solution
Given that $A$ is the area of rectangle $ABDE$ minus the area of region $EDC$. $$A \Rightarrow 4 - 2 \int_{0}^{1} \left(3 - x\right) - \left(\frac{x^2 + 3}{2}\right) \, dx$$ $$A \Rightarrow 4 - 2 \left\{ 3x - \frac{x^2}{2} - \frac{x^3}{6} - \frac{3}{2}x \right\}_{0}^{1}$$ $$A \Rightarrow 4 - 2 \left\{ 3 - \frac{1}{2} - \frac{1}{6} - \frac{3}{2} \right\} = \frac{7}{3}$$ So $6A = 14$
Question 8
Maths · Binomial Theorem · Single correct
The least value of $n$ for which the number of integral terms in the Binomial expansion of $\left( \sqrt[3]{7} + \sqrt[12]{11} \right)^n$ is 183, is:
2184
2196
2148
2172
Answer: (a)
Solution
General term = $\binom{n}{r} \left\{ 7^{1/3} \right\}^{n-r} \left( 11^{1/12} \right)^r$ $$= \binom{n}{r} \left\{ 7 \right\}^{\frac{n-r}{3}} (11)^{r/12}$$ For integral terms, $r$ must be a multiple of 12. Therefore, $r = 12k$, $k \in \mathbb{W}$. Total values of $r = 183$. Hence $\max \, r = 12(182) = 2184$. Min value of $n = 2184$.
Question 9
Maths · Complex Numbers and Quadratic Equations · Single correct
The number of solutions of the equation ($\frac{9}{x}$ - $\frac{9}{\sqrt{x}}$ + 2 ) ( $\frac{2}{x}$ - $\frac{7}{\sqrt{x}}$ + 3) = 0 is:
Let $y = y(x)$ be the solution of the differential equation $\cos x \left( \log_e (\cos x) \right)^2 \, \mathrm{d}y + \left( \sin x - 3y \sin x \log_e (\cos x) \right) \, \mathrm{d}x = 0, x \in \left( 0, \frac{\pi}{2} \right)$. If $y \left( \frac{\pi}{4} \right) = \frac{-1}{\log_e 2}$, then $y \left( \frac{\pi}{6} \right)$ is equal to:
Define a relation R on the interval $\left[0, \frac{\pi}{2}\right)$ by $xRy$ if and only if $\sec^2 x - \tan^2 y = 1$. Then R is :
both reflexive and transitive but not symmetric
an equivalence relation
reflexive but neither symmetric not transitive
both reflexive and symmetric but not transitive
Answer: (b)
Solution
Given $\sec^2 x - \tan^2 x = 1$ (on replacing $y$ with $x$). Reflexive: $$\sec^2 x - \tan^2 y = 1$$ $$1 + \tan^2 x + 1 - \sec^2 y = 1$$ $$\sec^2 y - \tan^2 x = 1$$ Symmetric: $$\sec^2 x - \tan^2 y = 1$$ $$\sec^2 y - \tan^2 z = 1$$ Adding both: $$\sec^2 x - \tan^2 y + \sec^2 y - \tan^2 z = 1 + 1$$ $$\sec^2 x + 1 - \tan^2 z = 2$$ $$\sec^2 x - \tan^2 z = 1$$ Transitive: Hence equivalence relation.
Question 12
Maths · Conic Sections · Single correct
Let the ellipse $E_1:\frac{x^2}{a^2}+\frac{y^2}{b^2}=1,\ a>b$ and $E_2:\frac{x^2}{A^2}+\frac{y^2}{B^2}=1,\ A<B$ have same eccentricity $\frac{1}{\sqrt{3}}$. Let the product of their lengths of latus rectums be $\frac{32}{\sqrt{3}}$, and the distance between the foci of $E_1$ be $4$. If $E_1$ and $E_2$ meet at $A,B,C$ and $D$, then the area of the quadrilateral $ABCD$ equals:
Consider an A. P. of positive integers, whose sum of the first three terms is 54 and the sum of the first twenty terms lies between 1600 and 1800. Then its 11^{th} term is:
90
84
122
108
Answer: (a)
Solution
Given $S_3 = 3a + 3d = 54$. This implies $a + d = 18$. $S_{20} = 10(2a + 19d)$ $$10(36 + 17d)$$ This implies $1600 < 10(36 + 17d) < 1800$. Therefore, $160 < 36 + 17d < 180$. This simplifies to $124 < 17d < 144$. Dividing throughout by 17 gives $\frac{7}{17} < d < \frac{8}{17}$. The common difference will be a natural number. Thus, $d = 8$ implies $a = 10$. Finally, $a_{11} = 10 + 10 \times 8 = 90$.
Question 14
Maths · Three Dimensional Geometry · Single correct
Let $\mathbf{a} = \hat{i} + 2\hat{j} + \hat{k}$ and $\mathbf{b} = 2\hat{i} + 7\hat{j} + 3\hat{k}$. Let $\mathbf{L}_1 : \mathbf{r} = (-\hat{i} + 2\hat{j} + \hat{k}) + \lambda \mathbf{a}, \lambda \in \mathbb{R}$ and $\mathbf{L}_2 : \mathbf{r} = (\hat{j} + \hat{k}) + \mu \mathbf{b}, \mu \in \mathbb{R}$ be two lines. If the line $\mathbf{L}_3$ passes through the point of intersection of $\mathbf{L}_1$ and $\mathbf{L}_2$, and is parallel to $\mathbf{a} + \mathbf{b}$, then $\mathbf{L}_3$ passes through the point:
Maths · Three Dimensional Geometry · Single correct
Let $\mathbf{L}_1 : \frac{x-1}{1} = \frac{y-2}{-1} = \frac{z-1}{2}$ and $\mathbf{L}_2 : \frac{x+1}{-1} = \frac{y-2}{2} = \frac{z}{1}$ be two lines. Let $\mathbf{L}_3$ be a line passing through the point $(\alpha, \beta, \gamma)$ and be perpendicular to both $\mathbf{L}_1$ and $\mathbf{L}_2$. If $\mathbf{L}_3$ intersects $\mathbf{L}_1$, then $|5\alpha - 11\beta - 8\gamma|$ equals:
Let $x_1, x_2, \ldots, x_{10}$ be ten observations such that $\sum_{i=1}^{10} (x_i - 2) = 30, \sum_{i=1}^{10} (x_i - \beta)^2 = 98, \beta > 2$, and their variance is $\frac{4}{5}$. If $\mu$ and $\sigma^2$ are respectively the mean and the variance of $2(x_1 - 1) + 4\beta, 2(x_2 - 1) + 4\beta, \ldots, 2(x_{10} - 1) + 4\beta$, then $\frac{\beta \mu}{\sigma^2}$ is equal to:
Let $\mathbf{A} = [a_{ij}] = \begin{bmatrix} \log_5 128 & \log_4 5 \\ \log_5 8 & \log_4 25 \end{bmatrix}$. If $A_{ij}$ is the cofactor of $a_{ij}$, $C_{ij} = \sum_{k=1}^{2} a_{ik} A_{jk}$, $1 \leq i,j \leq 2$, and $\mathbf{C} = [C_{ij}]$, then $8|\mathbf{C}|$ is equal to:
Let $f : (0, \infty) \to \mathbb{R}$ be a twice differentiable function. If for some $a = 0$, $\int_{0}^{1} f(\lambda x) \, \mathrm{d}\lambda = a f(x)$, $f(1) = 1$ and $f(16) = \frac{1}{8}$, then $16 - f'\left(\frac{1}{16}\right)$ is equal to _____.
Answer: 112
Solution
Given, $\int_0^1 f(\lambda x) d\lambda = a f(x)$ Let $\lambda x = u$ $d\lambda = \frac{1}{x} du$ From (1) $\frac{1}{x} \int_0^x f(u) du = a f(x)$ $$\Rightarrow \int_0^x f(u) du = ax f(x)$$ Differentiate both sides $$f(x) = a (x f'(x) + f(x))$$ $$\Rightarrow f(x) = ax f'(x) + a f(x)$$ $$\Rightarrow (1 - a) f(x) = ax f'(x)$$ $$\Rightarrow f'(x) = \frac{(1 - a)}{a} \cdot \frac{1}{x} f(x)$$ Integrate both sides w.r.t. $(x)$ $$\Rightarrow \int \frac{f'(x)}{f(x)} dx = \frac{(1 - a)}{a} \int \frac{1}{x} dx$$ $$\Rightarrow \ln f(x) = \left( \frac{1 - a}{a} \right) \ln x + c$$ Now at $x = 1, f(1) = 1$ $$\Rightarrow c = 0$$ Also given $f(16) = \frac{1}{8}$ $$\Rightarrow 1 = (16)^{\frac{1-a}{a}}$$ $$\Rightarrow 8 = 2^{\frac{4-4a}{a}}$$ $$\Rightarrow 2^{-3} = 2^{\frac{4-4a}{a}}$$ $$\Rightarrow -3 = \frac{4-4a}{a}$$ $$\Rightarrow -3a = 4 - 4a$$ $$\Rightarrow a = 4$$ $$\therefore f(x) = x^{-3/4}$$ $$f(x) = \frac{-3}{4} x^{-7/4}$$ Put $x = \frac{1}{16}$ $$f'\left(\frac{1}{16}\right) = \frac{-3}{4} \left(\frac{1}{16}\right)^{-7/4} = \frac{-3}{4} \cdot 2^{-4x\left(\frac{-7}{4}\right)} = -96$$ $$\therefore 16 - f'\left(\frac{1}{16}\right) \Rightarrow 16 - (-96) = 112$$
Question 22
Maths · Matrices · Numerical
Let $S = \left\{ m \in \mathbb{Z} : A^{m^2} + A^m = 3I - A^{-6} \right\}$, where $A = \begin{bmatrix} 2 & -1 \\ 1 & 0 \end{bmatrix}$. Then $n(S)$ is equal to
Answer: 2
Solution
Given $A = \begin{bmatrix} 2 & -1 \\ 1 & 0 \end{bmatrix}$. Now finding characteristic equation $$\begin{vmatrix} 2 - \lambda & -1 \\ 1 & -\lambda \end{vmatrix} = 0$$ $$\Rightarrow (2 - \lambda)(-\lambda) - (-1)(1) = -2\lambda + \lambda^2 + 1 = 0$$ $$\Rightarrow \lambda^2 - 2\lambda + 1 = 0$$ $$\Rightarrow (\lambda - 1)^2 = 0$$ $$\Rightarrow \lambda = 1$$ Since $A$ satisfies $(A - I)^2 = 0$. Therefore, $A = I + N$ where $N = A - I$. $$N = \begin{bmatrix} 1 & -1 \\ 1 & -1 \end{bmatrix}$$ $$N^2 = 0$$ $$A^m = (I + N)^m = I + mN$$ $$A^m \cdot A^m = (I + mN)(I + mN) = I + 2mN + m^2N^2$$ Since $N^2 = 0$ $$\Rightarrow A^{m^2} = I + 2mN$$ Now putting in given condition $$I + m^2N + I + mN = 3I - A^{-6}$$ $$A^{-1} = \begin{bmatrix} 0 & 1 \\ -1 & 2 \end{bmatrix}$$ $$A^{-6} = (A^{-1})^6 = I + (-6)N$$ Therefore, putting in (i) $$(m^2 + m)N = I - (I - 6N)$$ $$(m^2 + m)N = 6N$$ Since $N \neq 0$ $$\Rightarrow m^2 + m = 6$$ $$\Rightarrow m^2 + m - 6 = 0$$ $$\Rightarrow (m - 2)(m + 3) = 0$$ $$\Rightarrow m = 2, -3$$ Number of elements in $S$ is 2.
Question 23
Maths · Limits and Derivatives · Numerical
Let [t] be the greatest integer less than or equal to t. Then the least value of p $\in$ $\mathbb{N}$ for which $$\lim_{x \to 0^+} \left( x \left( \left\lfloor \frac{1}{x} \right\rfloor + \left\lfloor \frac{2}{x} \right\rfloor + \ldots + \left\lfloor \frac{p}{x} \right\rfloor \right) - x^2 \left( \left\lfloor \frac{1}{x^2} \right\rfloor + \left\lfloor \frac{2^2}{x^2} \right\rfloor + \ldots + \left\lfloor \frac{9^2}{x^2} \right\rfloor \right) \right) \geq 1$$ is equal to _______.
Answer: 24
Solution
Given $$\lim_{x \to 0^+} \left( x \left( \left\lfloor \frac{1}{x} \right\rfloor + \left\lfloor \frac{2}{x} \right\rfloor + \ldots + \left\lfloor \frac{p}{x} \right\rfloor \right) - x^2 \left( \left\lfloor \frac{1^2}{x^2} \right\rfloor + \left\lfloor \frac{2^2}{x^2} \right\rfloor + \left\lfloor \frac{9^2}{x^2} \right\rfloor \right) \right) \geq 1$$ The expression $$\left( 1 + 2 + \ldots + p \right) - \left( 1^2 + 2^2 + \ldots + 9^2 \right) \geq 1$$ This simplifies to $$\frac{p(p+1)}{2} - \frac{9 \cdot 10 \cdot 19}{6} \geq 1$$ Thus, $$p(p+1) \geq 572$$ The least natural value of $$p$$ is 24.
Question 24
Maths · Permutations and Combinations · Fill in the blank
The number of 6-letter words, with or without meaning, that can be formed using the letters of the word MATHS such that any letter that appears in the word must appear at least twice, is
Answer: 1405
Solution
Q6. (i) Single letter is used, then number of words = 5 (ii) Two distinct letters are used, then number of words $$^5C_2 \times \left( \frac{6!}{2!4!} \times 2 + \frac{6!}{3!3!} \right) = 10(30 + 20) = 500$$ (iii) Three distinct letters are used, then number of words $$^5C_3 \times \frac{6!}{2!2!2!} = 900$$ Total number of words = 1405
Let $S = \left\{ x : \cos^{-1} x = \pi + \sin^{-1} x + \sin^{-1} (2x + 1) \right\}$. Then $\sum_{x \in S} (2x - 1)^2$ is equal to
Answer: 5
Solution
Given $\cos^{-1} x = \pi + \sin^{-1} x + \sin^{-1}(2x + 1)$. $2 \cos^{-1} x - \sin^{-1}(2x + 1) = \frac{3\pi}{2}$. Let $2\alpha - \beta = \frac{3\pi}{2}$ where $\cos^{-1} x = \alpha$, $\sin^{-1}(2x + 1) = \beta$. Then $2\alpha = \frac{3\pi}{2} + \beta$. We have $\cos 2\alpha = \sin \beta$. Thus, $2 \cos^2 \alpha - 1 = \sin \beta$. Substituting, $2x^2 - 1 = 2x + 1$. This simplifies to $x^2 - x - 1 = 0$. Solving, $\Rightarrow n = \frac{1 \pm \sqrt{5}}{2}$. Therefore, $$n = \begin{cases} \frac{1+\sqrt{5}}{2} & rejected \\ \frac{1-\sqrt{5}}{2} & \end{cases}$$ Thus, $4x^2 - 4x = 4$. Finally, $(2x - 1)^2 = 5$.
Physics
Question 26
Physics · Alternating Current · Single correct
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Choke coil is simply a coil having a large inductance but a small resistance. Choke coils are used with fluorescent mercury-tube fittings. If household electric power is directly connected to a mercury tube, the tube will be damaged. Reason (R): By using the choke coil, the voltage across the tube is reduced by a factor $\left( \frac{R}{R^2 + \omega^2 L^2} \right)$, where $\omega$ is frequency of the supply across resistor $R$ and inductor $L$. If the choke coil were not used, the voltage across the resistor would be the same as the applied voltage. In the light of the above statements, choose the most appropriate answer from the options given below:
$(A)$ is true but $(R)$ is false
Both $(A)$ and $(R)$ are true and $(R)$ is the correct explanation of $(A)$
$(A)$ is false but $(R)$ is true
Both $(A)$ and $(R)$ are true but $(R)$ is not the correct explanation of $(A)$
Answer: (b)
Solution
The current $I$ in the circuit is given by the formula: $$I = \frac{V}{\sqrt{R^2 + \omega^2 L^2}}$$ The voltage across the resistor $V_R$ is given by: $$V_R = \frac{R}{\sqrt{R^2 + \omega^2 L^2}} V$$
Question 27
Physics · Motion in a Plane · Single correct
Two projectiles are fired with same initial speed from same point on ground at angles of $(45^\circ - \alpha)$ and $(45^\circ + \alpha)$, respectively, with the horizontal direction. The ratio of their maximum heights attained is:
$\frac{1 - \tan \alpha}{1 + \tan \alpha}$
$\frac{1 - \sin 2\alpha}{1 + \sin 2\alpha}$
$\frac{1 + \sin 2\alpha}{1 - \sin 2\alpha}$
$\frac{1 + \sin \alpha}{1 - \sin \alpha}$
Answer: (b)
Solution
The maximum height $H_{Max}$ is given by $$H_{Max} = \frac{(u \sin \theta)^2}{2g}$$ For $(H_{max})_1$, we have $u^2 \sin^2(45^\circ - \alpha)$. For $(H_{max})_2$, we have $u^2 \sin^2(45^\circ + \alpha)$. This can be expressed as $$\left( \frac{1}{\sqrt{2}} \cos \alpha - \frac{1}{\sqrt{2}} \sin \alpha \right)^2$$ which simplifies to $$\left( \frac{1}{\sqrt{2}} \cos \alpha + \frac{1}{\sqrt{2}} \sin \alpha \right)^2$$ Finally, this results in $$\frac{1 - \sin 2\alpha}{1 + \sin 2\alpha}$$
Question 28
Physics · Electric Charges and Fields · Single correct
An electric dipole of mass $m$, charge $q$, and length $l$ is placed in a uniform electric field $\mathbf{E} = E_0 \hat{i}$. When the dipole is rotated slightly from its equilibrium position and released, the time period of its oscillations will be:
$\frac{1}{2\pi} \sqrt{\frac{ml}{2qE_0}}$
$2\pi \sqrt{\frac{ml}{qE_0}}$
$\frac{1}{2\pi} \sqrt{\frac{2ml}{qE_0}}$
$2\pi \sqrt{\frac{ml}{2qE_0}}$
Answer: (d)
Solution
Given $\tau = PE_0 \sin \theta$. If $\theta$ is small, $\tau = -(PE_0) \theta$. $$I = m \left( \frac{l}{2} \right)^2 \cdot 2 = \frac{ml^2}{2}$$ $$T = 2\pi \sqrt{\frac{ml^2}{2 \cdot PE_0}} = 2\pi \sqrt{\frac{ml^2}{2 \cdot q/E_0}}$$ $$T = 2\pi \sqrt{\frac{ml}{2qE_0}}$$
Question 29
Physics · Physical World, Units and Measurements · Single correct
The pair of physical quantities not having same dimensions is:
Pressure and Young's modulus
Surface tension and impulse
Torque and energy
Angular momentum and Planck's constant
Answer: (b)
Solution
Q5. The dimension of angular momentum is $ML^2 T^{-1}$. The dimension of Planck's Constant is $ML^2 T^{-1}$. The dimension of torque is $ML^2 T^{-2}$. The dimension of energy is $ML^2 T^{-2}$. The dimension of surface tension is $MT^{-2}$. The dimension of impulse is $MLT^{-1}$. The dimension of pressure is $ML^{-1} T^{-2}$. The dimension of Young's modulus is $ML^{-1} T^{-2}$.
Question 30
Physics · Oscillations · Single correct
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Time period of a simple pendulum is longer at the top of a mountain than that at the base of the mountain. Reason (R): Time period of a simple pendulum decreases with increasing value of acceleration due to gravity and vice-versa. In the light of the above statements, choose the most appropriate answer from the options given below:
Both (A) and (R) are true and (R) is the correct explanation of (A)
is true but (R) is false
is false but (R) is true
Both (A) and (R) are true but (R) is not the correct explanation of (A)
Physics · Physical World, Units and Measurements · Single correct
The expression given below shows the variation of velocity $(v)$ with time $(t)$, $v = At^2 + \frac{Bt}{C+t}$. The dimension of $ABC$ is:
$[M^0 L^1 T^{-3}]$
$[M^0 L^2 T^{-2}]$
$[M^0 L^1 T^{-2}]$
$[M^0 L^2 T^{-3}]$
Answer: (d)
Solution
Given $[LT^{-1}] = [A][T^2] = \frac{[B][T]}{[C] + [T]}$. We have $[C] = [T]$, $[A] = [LT^{-3}]$, $[B] = [LT^{-1}]$, and $[ABC] = [L^2 T^{-3}]$.
Question 32
Physics · Electromagnetic Induction · Single correct
Consider $I_1$ and $I_2$ as the currents flowing simultaneously in two nearby coils $1$ and $2$, respectively. If $L_1$ is the self-inductance of coil $1$ and $M_{12}$ is the mutual inductance of coil $1$ with respect to coil $2$, then the induced emf in coil $1$ is:
Given $\phi_1 = L_1 I_1 + M_{12} I_2$. The expression for $\varepsilon_1$ is given by $$\varepsilon_1 = -\frac{d\phi_1}{dt} = -L_1 \frac{dI_1}{dt} - M_{12} \frac{dI_2}{dt}.$$
Question 33
Physics · Ray Optics and Optical Instruments · Single correct
At the interface between two materials having refractive indices $n_1$ and $n_2$, the critical angle for reflection of an em wave is $\theta_{1C}$. The $n_2$ material is replaced by another material having refractive index $n_3$ such that the critical angle at the interface between $n_1$ and $n_3$ materials is $\theta_{2C}$. If $n_3 > n_2 > n_1$; $\frac{n_2}{n_3} = \frac{2}{5}$ and $\sin \theta_{2C} - \sin \theta_{1C} = \frac{1}{2}$, then $\theta_{1C}$ is
Physics · Moving Charges and Magnetism · Single correct
Consider a long straight wire of a circular cross-section (radius a) carrying a steady current I. The current is uniformly distributed across this cross-section. The distances from the centre of the wire's cross-section at which the magnetic field [inside the wire, outside the wire] is half of the maximum possible magnetic field, any where due to the wire, will be
[a/4, 3a/2]
[a/4, 2a]
[a/2, 2a]
[a/2, 3a]
Answer: (c)
Solution
Maximum possible magnetic field is at the surface. $$B_{max} = \frac{\mu_0 I}{2 \pi a}$$ $$\frac{B_{max}}{2} = \frac{\mu_0 I}{4 \pi a}$$ It can be obtained inside as well as outside the wire. For inside, $$\frac{\mu_0 I}{4 \pi a} = \frac{\mu_0 I r}{2 \pi a^2}$$ $$\Rightarrow r = \frac{a}{2}$$ For outside, $$\frac{\mu_0 I}{4 \pi a} = \frac{\mu_0 I}{2 \pi r}$$ $$\Rightarrow r = 2a$$ Correct answer $\left[ \frac{a}{2}, 2a \right]$
Question 35
Physics · Work, Energy and Power · Single correct
As shown below, bob $A$ of a pendulum having massless string of length $'R'$ is released from $60^\circ$ to the vertical. It hits another bob $B$ of half the mass that is at rest on a frictionless table in the center. Assuming elastic collision, the magnitude of the velocity of bob $A$ after the collision will be (take $g$ as acceleration due to gravity)
$\frac{4}{3} \sqrt{Rg}$
$\frac{2}{3} \sqrt{Rg}$
$\sqrt{Rg}$
$\frac{1}{3} \sqrt{Rg}$
Answer: (d)
Solution
Velocity of a just before hitting: $$u = \sqrt{2g \frac{R}{2}} = \sqrt{gR}$$ Just after collision, let velocity of A and B are $v_1$ and $v_2$ respectively. Therefore, by COM: $$mu = mv_1 + \frac{m}{2} v_2$$ $$2v_1 + v_2 = 2u \ldots (i)$$ $$e = 1 = \frac{v_2 - v_1}{u}$$ $$\Rightarrow v_2 - v_1 = u \ldots (ii)$$ From (i) -(ii) $$\Rightarrow 3v_1 = u \Rightarrow v_1 = \frac{u}{3} = \frac{1}{3} \sqrt{gR}$$
Question 36
Physics · Dual Nature of Radiation and Matter · Single correct
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason ($R$). Assertion (A): Emission of electrons in photoelectric effect can be suppressed by applying a sufficiently negative electron potential to the photoemissive substance. Reason ($R$): A negative electric potential, which stops the emission of electrons from the surface of a photoemissive substance, varies linearly with frequency of incident radiation. In the light of the above statements, choose the most appropriate answer from the options given below:
(A) is false but ($R$) is true
(A) is true but ($R$) is false
Both (A) and ($R$) are true and ($R$) is the correct explanation of (A)
Both (A) and ($R$) are true but ($R$) is not the correct explanation of (A)
Answer: (d)
Solution
Negative potential will slow the electrons and if it is sufficient, it will make the photocurrent zero. $$eVs = hf - \phi_0$$
Question 37
Physics · Electromagnetic Induction · Single correct
A coil of area A and N turns is rotating with angular velocity $\omega$ in a uniform magnetic field $\vec{B}$ about an axis perpendicular to $\vec{B}$. Magnetic flux $\phi$ and induced emf $\varepsilon$ across it, at an instant when $\vec{B}$ is parallel to the plane of coil, are:
$\varphi = AB, \varepsilon = 0$
$\varphi = 0, \varepsilon = 0$
$\varphi = 0, \varepsilon = NAB\omega$
$\varphi = AB, \varepsilon = NAB\omega$
Answer: (c)
Solution
Given $\phi = BAN \cdot \cos(\omega t)$. The induced emf $\varepsilon$ is given by $$\varepsilon = -\frac{d\phi}{dt} = BA\omega N \cdot \sin(\omega t).$$ When $B$ is parallel to the plane, $\omega t = \frac{\pi}{2}$. Thus, $\phi = 0$, and $\varepsilon = BA\omega N$.
Question 38
Physics · Mechanical Properties of Fluids · Single correct
The fractional compression $\left( \frac{\Delta V}{V} \right)$ of water at the depth of 2.5 km below the sea level is ______ $\%$. Given, the Bulk modulus of water $= 2 \times 10^9 \, \mathrm{N \, m^{-2}}$, density of water $= 10^3 \, \mathrm{kg \, m^{-3}}$, acceleration due to gravity $= g = 10 \, \mathrm{m \, s^{-2}}$.
Physics · Dual Nature of Radiation and Matter · Single correct
If $\lambda$ and $K$ are de Broglie wavelength and kinetic energy, respectively, of a particle with constant mass. The correct graphical representation for the particle will be
Physics · Semiconductor Electronics: Materials, Devices and Simple Circuits · Single correct
For the circuit shown above, equivalent GATE is:
OR gate
NAND gate
NOT gate
AND gate
Answer: (a)
Solution
The truth table is given as follows: \begin{tabular}{|c|c|c|} \hline A & B & Y \\ \hline 0 & 0 & 0 \\ \hline 0 & 1 & 1 \\ \hline 1 & 0 & 1 \\ \hline 1 & 1 & 1 \\ \hline \end{tabular} This is the truth table for an OR Gate.
Question 41
Physics · System of Particles and Rotational Motion · Single correct
A body of mass 'm' connected to a massless and unstretchable string goes in verticle circle of radius 'R' under gravity g. The other end of the string is fixed at the center of circle. If velocity at top of circular path is $n \sqrt{gR}$, where, $n \geq 1$, then ratio of kinetic energy of the body at bottom to that at top of the circle is
$\frac{n^2}{n^2 + 4}$
$\frac{n^2 + 4}{n^2}$
$\frac{n + 4}{n}$
$\frac{n}{n + 4}$
Answer: (b)
Solution
Given $v = n \sqrt{gR}$. The initial velocity $v_0$ is given by $$v_0 = \sqrt{v^2 + 2g(2R)}$$ Substituting $v = n \sqrt{gR}$, we have $$v_0 = \sqrt{n^2 gR + 4gR}$$ Therefore, $$\frac{k_{bottom}}{k_{trog}} = \frac{v_0^2}{v^2} = \frac{n^2 + 4}{n^2}$$
Question 42
Physics · Ray Optics and Optical Instruments · Single correct
Let $u$ and $v$ be the distances of the object and the image from a lens of focal length $f$. The correct graphical representation of $u$ and $v$ for a convex lens when $|u| > f$ is
Answer: (c)
Solution
Given the equation $(u + f)(v - f) = f^2$. The graph shows the relationship between $u$ and $v$. The axes are labeled $u$ and $v$ respectively.
Question 43
Physics · Electric Charges and Fields · Single correct
Match List - I with List - II. \vspace{0.3cm} \[ \begin{array}{clcl} \textbf{List-I} & & \textbf{List-II} & \\ (A) & \text{Electric field inside (distance } r > 0 \text{ from center) of a uniformly charged spherical shell} & (I) & \dfrac{\sigma}{\varepsilon_0}\\ & \text{with surface charge density } \sigma \text{, and radius } R. & (II) & \dfrac{\sigma}{2\varepsilon_0}\\ (B) & \text{Electric field at distance } r > 0 \text{ from a uniformly charged infinite plane sheet} & (III) & 0\\ & \text{with surface charge density } \sigma. & (IV) & \dfrac{\sigma R^2}{\varepsilon_0 r^2}\\ (C) & \text{Electric field outside (distance } r > 0 \text{ from center) of a uniformly charged spherical shell} & & \\ & \text{with surface charge density } \sigma \text{, and radius } R. & & \\ (D) & \text{Electric field between 2 oppositely charged infinite plane parallel sheets with uniform} & & \\ & \text{surface charge density } \sigma. & & \end{array} \] \vspace{0.3cm} Choose the correct answer from the options given below:
The workdone in an adiabatic change in an ideal gas depends upon only:
change in its temperature
change in its volume
change in its pressure
change in its specific heat
Answer: (a)
Solution
Work done in adiabatic process is given by $$\frac{nR \Delta T}{1 - \gamma}$$. So, it depends upon change in temperature.
Question 45
Physics · Electromagnetic Waves · Single correct
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason ($R$). Assertion (A) : Electromagnetic waves carry energy but not momentum. Reason ($R$): Mass of a photon is zero. In the light of the above statements, choose the most appropriate answer from the options given below :
Both (A) and ($R$) are true and ($R$) is the correct explanation of (A)
Both (A) and ($R$) are true but ($R$) is not the correct explanation of (A)
(A) is false but ($R$) is true
(A) is true but ($R$) is false
Answer: (c)
Solution
EM wave carry both energy and momentum. Rest mass of photon is zero.
Question 46
Physics · System of Particles and Rotational Motion · Numerical
The coordinates of a particle with respect to origin in a given reference frame is $(1, 1, 1)$ meters. If a force of $\vec{F} = \hat{i} - \hat{j} + \hat{k}$ acts on the particle, then the magnitude of torque (with respect to origin) in z-direction is
$1$
$2$
$3$
$\sqrt{3}$
Answer: (b)
Solution
The torque $\vec{\tau}$ acting on the particle with respect to the origin can be calculated using the cross product of the position vector $\vec{r}$ and the force vector $\vec{F}$: $$\vec{\tau} = \vec{r} \times \vec{F}$$ Given the position vector $\vec{r} = (1, 1, 1) \, \mathrm{m}$ and the force vector $\vec{F} = \hat{i} - \hat{j} + \hat{k}$, we need to calculate the cross product: $$\vec{\tau} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 1 & 1 & 1 \\ 1 & -1 & 1 \end{vmatrix}$$ Calculating the determinant, we have: $$\vec{\tau} = \hat{i}(1 \cdot 1 - 1 \cdot (-1)) - \hat{j}(1 \cdot 1 - 1 \cdot 1) + \hat{k}(1 \cdot (-1) - 1 \cdot 1)$$ This simplifies to: $$\vec{\tau} = \hat{i}(1 + 1) - \hat{j}(1 - 1) + \hat{k}(-1 - 1)$$ $$\vec{\tau} = 2\hat{i} - 0\hat{j} - 2\hat{k}$$ The torque vector is $\vec{\tau} = 2\hat{i} - 2\hat{k}$. To find the magnitude of the torque in the $z$-direction, we look at the $\hat{k}$ component: $$\tau_z = -2$$ The magnitude of torque in the $z$-direction is: $$|\tau_z| = 2 \, \mathrm{Nm}$$ Thus, the magnitude of the torque in the $z$-direction is 2 Newton-meters.
Question 47
Physics · Kinetic Theory · Fill in the blank
A container of fixed volume contains a gas at $27^\circ \mathrm{C}$. To double the pressure of the gas, the temperature of gas should be raised to _____$^\circ \mathrm{C}$.
Answer: 327
Solution
Given $V = constant$, we have the relation $$\frac{P_1}{T_1} = \frac{P_2}{T_2}.$$ Given $P_2 = 2P_1$ and $T_2 = 2T_1$, we find $$T_2 = 2 \times 300 = 600 \, K.$$ Therefore, $T_2 = 327^\circ C$.
Question 48
Physics · Ray Optics and Optical Instruments · Numerical
Two light beams fall on a transparent material block at point 1 and 2 with angle $\theta_1$ and $\theta_2$, respectively, as shown in figure. After refraction, the beams intersect at point 3 which is exactly on the interface at other end of the block. Given: the distance between 1 and 2, $d=4\sqrt{3}\,\mathrm{cm}$ and $\theta_1=\theta_2=\cos^{-1}\left(\frac{n_2}{2n_1}\right)$, where refractive index of the block $n_2>$ refractive index of the outside medium $n_1$, then the thickness of the block is $\underline{\hspace{2cm}}$ cm.
Physics · Mechanical Properties of Fluids · Numerical
In a hydraulic lift, the surface area of the input piston is $6 \, \mathrm{cm}^2$ and that of the output piston is $1500 \, \mathrm{cm}^2$. If $100 \, \mathrm{N}$ force is applied to the input piston to raise the output piston by $20 \, \mathrm{cm}$, then the work done is ______ kJ.
Answer: 5
Solution
Given $F = 100 \, \mathrm{N}$, $A_1 = 6 \, \mathrm{cm^2}$, and $A_2 = 1500 \, \mathrm{cm^2}$. Using the formula $\frac{F_1}{A_1} = \frac{F_2}{A_2}$, we have: $$\frac{100}{6} = \frac{F}{1500}$$ Solving for $F$ gives: $$F = \frac{50}{3} \times 1500$$ Calculating $F$: $$F = 50 \times 500 = 25 \times 10^3 \, \mathrm{N}$$ The work done $\omega$ is given by $\vec{F} \cdot \vec{S}$: $$\omega = 25 \times 10^3 \times \frac{20}{100}$$ Simplifying gives: $$= 5 \times 10^3 = 5 \, \mathrm{kJ}$$
Question 50
Physics · Motion in a Plane · Numerical
The maximum speed of a boat in still water is $27 \, \mathrm{km/h}$. Now this boat is moving downstream in a river flowing at $9 \, \mathrm{km/h}$. A man in the boat throws a ball vertically upwards with speed of $10 \, \mathrm{m/s}$. Range of the ball as observed by an observer at rest on the river bank, is ______ cm. (Take $g = 10 \, \mathrm{m/s^2}$)
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Total number of nucleophiles from the following is: $\mathrm{NH_3}$, $\mathrm{PhSH}$, $\mathrm{(H_3C)_2S}$, $\mathrm{H_2C=CH_2}$, $\overset{\ominus}{\mathrm{O}}\mathrm{H}$, $\mathrm{H_3O^\oplus}$, $\mathrm{(CH_3)_2CO}$, $\mathrm{>=NCH_3}$
7
4
6
5
Answer: (d)
Solution
Total five nucleophiles are present: $\mathrm{NH_3}$, $\mathrm{PhSH}$, $(\mathrm{H_3C})_2\mathrm{S}$, $\mathrm{CH_2} = \mathrm{CH_2}$, $\overset{\ominus}{\mathrm{O}}\mathrm{H}$.
Question 52
Chemistry · Electrochemistry · Single correct
The standard reduction potential values of some of the p-block ions are given below. Predict the one with the strongest oxidising capacity.
The element having strongest oxidising capacity will have highest value of standard reduction potential.
Question 53
Chemistry · Electrochemistry · Single correct
The molar conductivity of a weak electrolyte when plotted against the square root of its concentration, which of the following is expected to be observed?
A small decrease in molar conductivity is observed at infinite dilution.
Molar conductivity decreases sharply with increase in concentration.
A small increase in molar conductivity is observed at infinite dilution.
Molar conductivity increases sharply with increase in concentration.
Answer: (b)
Solution
For a weak electrolyte, the variation of $\Lambda_m$ with $\sqrt{c}$ is shown in the graph. The graph depicts a curve that decreases as $\sqrt{c}$ increases.
Question 54
Chemistry · Equilibrium · Single correct
At temperature T, compound $\mathrm{AB}_2{(g)}$ dissociates as $\mathrm{AB}_2{(g)} \rightleftharpoons \mathrm{AB}{(g)} + \frac{1}{2} \mathrm{B}_2{(g)}$ having degree of dissociation $x$ (small compared to unity). The correct expression for $x$ in terms of $K_p$ and $p$ is
$\sqrt[4]{\frac{2K_p}{p}}$
$\sqrt[3]{\frac{2K_p}{p}}$
$\sqrt[3]{\frac{2K_p^2}{p}}$
$\sqrt{\frac{K_p}{p}}$
Answer: (b)
Solution
For the reaction $\mathrm{AB_2(g) \rightleftharpoons AB(g) + \frac{1}{2} B_2(g)}$, at time $t = 0$, the initial pressure is $p_0$. At equilibrium, $t = t_{eq}$, the pressures are $p_0(1-x)$ for $\mathrm{AB_2}$, $p_0 x$ for $\mathrm{AB}$, and $\frac{p_0 x}{2}$ for $\mathrm{B_2}$. The total pressure $p$ is given by: $$p = p_0 x - p_0 x + p_0 x + \frac{p_0 x}{2}$$ Simplifying, we have: $$p = p_0 \left(1 + \frac{x}{2}\right)$$ Thus, $p_0$ is: $$p_0 = \frac{p}{\left(1 + \frac{x}{2}\right)}$$ The equilibrium constant $K_p$ is: $$K_p = \left( p_{AB} \right) \left( p_{B_2} \right)^{1/2}$$ Substituting the pressures, we get: $$K_p = \left( p_{0} x \right) \left( \frac{p_{0} x}{2} \right)^{1/2}$$ Simplifying further: $$K_p = \frac{p_0 (1-x)}{\left(1 + \frac{x}{2}\right)} \left( \frac{p}{1 + \frac{x}{2}} \times \frac{x}{2} \right)^{1/2}$$ Since $x \ll 1$, we approximate: $$K_p = p^{1/2} x^{3/2} \left(2\right)^{1/2}$$ Solving for $x$, we have: $$x = \sqrt[3]{\frac{2 K_p^2}{p}}$$
Question 55
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Match List - I with List - II. List - I Choose the correct answer from the options given below:
(A)-(II), (B)-(III), (C)-(IV), (D)-(I)
(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
(A)-(III), (B)-(II), (C)-(I), (D)-(IV)
(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
Answer: (a)
Solution
The structure in option (A) is a linear chain with an ethyl group at the third carbon and a methyl group at the fifth carbon. This corresponds to the name 3-Ethyl-5-methylheptane. The structure in option (B) is a different configuration.
Question 56
Chemistry · Some Basic Concepts of Chemistry · Single correct
Choose the correct statements. (A) Weight of a substance is the amount of matter present in it. (B) Mass is the force exerted by gravity on an object. (C) Volume is the amount of space occupied by a substance. (D) Temperatures below $0^\circ \mathrm{C}$ are possible in Celsius scale, but in Kelvin scale negative temperature is not possible. (E) Precision refers to the closeness of various measurements for the same quantity. Choose the correct answer from the options given below:
(A), (D) and (E) Only
(C), (D) and (E) Only
(A), (B) and (C) Only
(B), (C) and (D) Only
Answer: (b)
Solution
Mass of substance is amount of matter present in it. Weight is force exerted by gravity on object.
Question 57
Chemistry · Co-ordination Compounds · Single correct
The correct increasing order of stability of the complexes based on $\Delta_o$ value is: I. $[\mathrm{Mn(CN)}_6]^{3-}$ II. $[\mathrm{Co(CN)}_6]^{4-}$ III. $[\mathrm{Fe(CN)}_6]^{4-}$ IV. $[\mathrm{Fe(CN)}_6]^{3-}$
IV < III < II < I
I < II < IV < III
III < II < IV < I
II < III < I < IV
Answer: (b)
Solution
Neglecting pairing energy I. $[\mathrm{Mn(CN)B}]^{3-} \Rightarrow \mathrm{Mn}^{3+}, \ t_2 \ g^4$, CFSE $= -0.4 \times 4 \Delta o = -1.6 \Delta$. II. $[\mathrm{Co(CN)8}]^{4-} \Rightarrow \mathrm{Co}^{2+}, \ t_2^6 e_g^1$, CFSE $= -0.4 \times 6 + 0.6 \times 1 = -1.8 \Delta$ III. $[\mathrm{Fe(CN)8}]^{4-} \Rightarrow \mathrm{Fe}^{2+}, \ t_{2g}^6 e_g^0$, CFSE $= -0.4 \times 6 = -2.4 \Delta_0$ IV. $[\mathrm{Fe(CN)8}]^{3-} \Rightarrow \mathrm{Fe}^{3+}, \ t_{2g}^5 e_g^0$, CFSE $= -0.4 \times 5 = -2 \Delta_0$ Order of stability III > IV > II > I
Question 58
Chemistry · Co-ordination Compounds · Single correct
Match List - I with List - II. Choose the correct answer from the options given below :
(A) - (IV), (B) - (II), (C) - (I), (D) - (III)
(A) - (III), (B) - (I), (C) - (II), (D) - (IV)
(A) - (IV), (B) - (I), (C) - (II), (D) - (III)
(A) - (III), (B) - (II), (C) - (I), (D) - (IV)
Answer: (a)
Solution
For (A) $[\mathrm{MnBr_4}]^{2-}$, $\mathrm{Mn}^{+2} \Rightarrow [\mathrm{Ar}] 3d^5$. In presence of ligand field: $$\Rightarrow [\mathrm{Ar}] \uparrow \uparrow \uparrow \uparrow \uparrow \square \square \square$$ This leads to $sp^3$ hybridization, paramagnetic in nature. For (B) $[\mathrm{FeF_6}]^{3-}$, $\mathrm{Fe}^{+3} \Rightarrow [\mathrm{Ar}] 3d^5$. In presence of ligand field: $$\Rightarrow [\mathrm{Ar}] \uparrow \uparrow \uparrow \uparrow \uparrow \square \square \square \square \square \square$$ This leads to $sp^3d^2$ hybridization, paramagnetic in nature. For (C) $[\mathrm{Co(C_2O_4)_3}]^{3-}$, $\mathrm{Co}^{+3} \Rightarrow [\mathrm{Ar}] 3d^6$. In presence of ligand field: $$\Rightarrow [\mathrm{Ar}] \uparrow\downarrow \uparrow\downarrow \uparrow\downarrow \square \square \square$$ This leads to $d^2sp^3$ hybridization, diamagnetic in nature. For (D) $[\mathrm{Ni(CO)_4}]$, $\mathrm{Ni}^{0} \Rightarrow [\mathrm{Ar}] 3d^8 4s^2$. In presence of ligand field: $$\Rightarrow [\mathrm{Ar}] \uparrow\downarrow \uparrow\downarrow \uparrow\downarrow \uparrow\downarrow \uparrow\downarrow \square \square$$ This leads to $sp^3$ hybridization, diamagnetic in nature.
Question 59
Chemistry · Hydrocarbons · Single correct
In the following substitution reaction: product 'P' formed is:
Answer: (d)
Solution
Br at the para position of $\mathrm{NO_2}$ will undergo aromatic nucleophilic substitution by nucleophile $\mathrm{C_2H_5ONa}$.
Question 60
Chemistry · Electrochemistry · Single correct
For a Mg $\mid$ Mg$^{2+}$ (aq) $\mid$ Ag$^{+}$ (aq) $\mid$ Ag the correct Nernst Equation is:
$1.24\,\mathrm{g}$ of $\mathrm{AX_2}$ (molar mass $124\,\mathrm{g\,mol^{-1}}$) is dissolved in $1\,\mathrm{kg}$ of water to form a solution with a boiling point of $100.0156^\circ\mathrm{C}$. Similarly, $25.4\,\mathrm{g}$ of $\mathrm{AY_2}$ (molar mass $250\,\mathrm{g\,mol^{-1}}$) dissolved in $2\,\mathrm{kg}$ of water constitutes a solution with a boiling point of $100.0260^\circ\mathrm{C}$. Given: $K_b(\mathrm{H_2O})=0.52\,\mathrm{K\,kg\,mol^{-1}}$.
$\mathrm{AX_2}$ is fully ionised while $\mathrm{AY_2}$ is completely unionised.
$\mathrm{AX_2}$ is completely unionised while $\mathrm{AY_2}$ is fully ionised.
$\mathrm{AX_2}$ and $\mathrm{AY_2}$ (both) are completely unionised.
$\mathrm{AX_2}$ and $\mathrm{AY_2}$ (both) are fully ionised
Answer: (a)
Solution
For $\mathrm{AX_2}$ $$\Delta T_b = i \, K \, m$$ $$0.0156 = i \times 0.52 \times \frac{1.24}{124 \times 1}$$ $$3 = i$$ $$3 = 1 + 2\alpha$$ $$1 = \alpha$$ For $\mathrm{AY_2}$ $$\Delta T_b = i \, K_b \, m$$ $$0.0260 = i \times 0.52 \times \frac{25.4}{250 \times 2}$$ $$i \approx 1$$ Therefore, $\mathrm{AX_2}$ is completely ionised and $\mathrm{AY_2}$ is completely unionised.
Question 63
Chemistry · Thermodynamics · Single correct
$500\,\mathrm{J}$ of energy is transferred as heat to $0.5\,\mathrm{mol}$ of Argon gas at $298\,\mathrm{K}$ and $1.00\,\mathrm{atm}$. The final temperature and the change in internal energy respectively are: Given: $R=8.3\,\mathrm{J\,K^{-1}\,mol^{-1}}$
378 \, \mathrm{K} and 500 \, \mathrm{J}
368 \, \mathrm{K} and 500 \, \mathrm{J}
348 \, \mathrm{K} and 300 \, \mathrm{J}
378 \, \mathrm{K} and 300 \, \mathrm{J}
Answer: (d)
Solution
Given $q_p = n \times c_p \times \Delta T$. $$500 = 0.5 \times \frac{5}{2} \times 8.3 \left( T_f - 298 \right)$$ Therefore, $T_f \approx 346.2 \, \mathrm{K}$. The ratio $\frac{\Delta H}{\Delta U} = \frac{C_p}{C_v} = \left( \frac{5}{3} \right)$. Thus, $\Delta U = \frac{3}{5} \times 500 = 300 \, \mathrm{J}$.
Question 64
Chemistry · Chemical Kinetics and Nuclear Chemistry · Single correct
The reaction $\mathrm{A_2+B_2\rightarrow2AB}$ follows the mechanism $$\mathrm{A_2\underset{k_{-1}}{\overset{k_1}{\rightleftharpoons}}A+A}\ \text{(fast)}$$ $$\mathrm{A+B_2\xrightarrow{k_2}AB+B}\ \text{(slow)}$$ $$\mathrm{A+B\rightarrow AB}\ \text{(fast)}$$ The overall order of the reaction is:
2
2.5
3
1.5
Answer: (d)
Solution
Given the rate equation $rate = k_2 [A] [B_2]$. $$\left( \frac{k_1}{k_{-1}} \right) = \left( \frac{[A]^2}{[A_2]} \right)$$ This implies $[A] = \sqrt{\frac{k_1}{k_{-1}}} \cdot \sqrt{[A_2]}$. Substituting in (1), we get $$Rate = k_2 \sqrt{\frac{k_1}{k_{-1}}} \cdot [A_2]^{\frac{1}{2}} \cdot [B_2]$$ Therefore, the order is $$\left( \frac{3}{2} \right) = 1.5$$
Question 65
Chemistry · Structure of Atom · Single correct
If $a_0$ is denoted as the Bohr radius of hydrogen atom, then what is the de-Broglie wavelength $(\lambda)$ of the electron present in the second orbit of hydrogen atom? [n : any integer]
$\frac{8\pi a_0}{n}$
$\frac{2a_0}{n\pi}$
$\frac{4n}{\pi a_0}$
$\frac{4\pi a_0}{n}$
Answer: (c)
Solution
Bohr radius of hydrogen atom $\rightarrow a_0$ According to Bohr, the equation used to calculate the angular momentum of an electron in a hydrogen atom is $$mvr = \frac{nh}{2\pi} \ldots (i)$$ $m \rightarrow$ mass of electron $v \rightarrow$ velocity of electron $r \rightarrow$ radius of the orbit $n \rightarrow$ orbit number in which electron is present. Given that the electron is present in the second orbit, $n = 2$. The radius of the second orbit $r_2 = a_0 \times 2^2 = 4a_0$. General formula for radius of $n^{th}$ orbit, $$r_n = a_0 \times n^2$$ From (1) $$mvr = n \frac{h}{2\pi}$$ $$2\pi r = n \frac{h}{mv}$$ $\frac{h}{mv} = \lambda$ (de Broglie relationship, $\lambda \rightarrow$ de Broglie Wavelength) So, $2\pi r = n\lambda$. For the electron in the second orbit, $2\pi r_2 = n\lambda$. Substitute for $r_2$ $$2\pi \times 4a_0 = n\lambda$$ $$8\pi a_0 = n\lambda$$ Therefore, $\lambda = \frac{8\pi a_0}{n}$.
Question 66
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
The product (P) formed in the following reaction is :
Answer: (a)
Solution
It is Clemmensen reduction, it will not reduce ester. Ester cannot be reduced by Clemmensen reduction.
Question 67
Chemistry · Classification of Elements and Periodicity in Properties · Single correct
An element $E'$ has the ionisation enthalpy value of $374 \, \mathrm{kJ \, mol^{-1}}$. $E'$ reacts with elements $A, B, C$ and $D$ with electron gain enthalpy values of $-328, -349, -325$ and $-295 \, \mathrm{kJ \, mol^{-1}}$, respectively. The correct order of the products $\mathrm{EA, EB, EC}$ and $\mathrm{ED}$ in terms of ionic character is:
$\mathrm{ED > EC > EB > EA}$
$\mathrm{EA > EB > EC > ED}$
$\mathrm{EB > EA > EC > ED}$
$\mathrm{ED > EC > EA > EB}$
Answer: (c)
Solution
The element having high value of Electron gain enthalpy (magnitude) will form a compound having higher ionic character so order of ionic character $$EB > EA > EC > ED$$
Question 68
Chemistry · Co-ordination Compounds · Single correct
Match List - I with List - II. Choose the correct answer from the options given below :
(A)-(IV), (B)-(I), (C)-(III), (D)-(II)
(A)-(III), (B)-(II), (C)-(I), (D)-(IV)
(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
(A)-(IV), (B)-(I), (C)-(II), (D)-(III)
Answer: (d)
Solution
Amylose: It is a plant based starch it has $\alpha - C_1 - C_4$ glycosidic linkage. Cellulose: It has $\beta - C_1 - C_4$ glycosidic linkage. Glycogen: It has $\alpha - C_1 - C_4$ and glycosidic linkage (animal starch). Amylopectin: It is a plant based with $\alpha - C_1 - C_4$ and $C_1 - C_6$ glycosidic linkage.
Question 69
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
The steam volatile compounds among the following are:
and (D) Only
and (C) Only
, (B) and (C) Only
and (B) Only
Answer: (d)
Solution
Both compounds (A) and (B) are steam volatile due to intramolecular hydrogen bonding.
Question 70
Chemistry · Classification of Elements and Periodicity in Properties · Single correct
Given below are two statements: **Statement (I):** The radii of isoelectronic species increases in the order: $\mathrm{Mg^{2+} F>Br>I}$ In the light of the above statements, choose the most appropriate answer from the options given below:
Statement I is incorrect but Statement II is correct
Statement I is correct but Statement II is incorrect
Both Statement I and Statement II are incorrect
Both Statement I and Statement II are correct
Answer: (d)
Solution
Given $r \propto q^{-}$ (for isoelectronic species) and $\propto \frac{1}{q^{+}}$. Therefore, Statement I is correct. Magnitude of electron gain enthalpy: $\mathrm{Cl} > \mathrm{F} > \mathrm{Br} > \mathrm{I}$.
Question 71
Chemistry · Amines · Numerical
Given below are some nitrogen containing compounds Each of them is treated with HCl separately. 1.0 g of the most basic compound will consume _______ mg of HCl. (Given molar mass in $\mathrm{g/mol}^{-1}$ C : 12, H : 1, O : 16, Cl : 35.5)
Answer: 341
Solution
Benzyl Amine is most basic due to localised lone pair. Mole of benzyl Amine $\Rightarrow \frac{1}{107} = 0.00934$ mole 1 Mole of Benzyl amine consumed 1 mole of HCl So, Mole of HCl consumed $\rightarrow 0.00934$ mole Mass of HCl consumed $\rightarrow 0.00934 \times$ molar mass of HCl $$= 0.00934 \times 36.5$$ $$= 0.341 \, \mathrm{gm}$$ $$= 341 \, \mathrm{mg}$$
Question 72
Chemistry · The d-and f-Block Elements · Numerical
The molar mass of the water insoluble product formed from the fusion of chromite ore ($\mathrm{FeCr_2O_4}$) with $\mathrm{Na_2CO_3}$ in presence of $\mathrm{O_2}$ is $\mathrm{gmol^{-1}}$.
Answer: 160
Solution
The insoluble product will be $\mathrm{Fe_2O_3}$. The molar mass is calculated as follows: molar mass $= 56 \times 2 + 16 \times 3$ $$= 112 + 48$$ $$= 160$$
Question 73
Chemistry · Chemical Bonding and Molecular Structure · Numerical
The sum of sigma ($\sigma$) and pi ($\pi$) bonds in Hex-1,3-dien-5-yne is .
Answer: 15
Solution
Number of $\sigma$ bond $= 11$. Number of $\pi$ bond $= 4$. $$\sigma + \pi = 11 + 4 = 15$$
Question 74
Chemistry · Solutions · Numerical
If $\mathrm{A}_2 \mathrm{B}$ is $30\%$ ionised in an aqueous solution, then the value of van't Hoff factor (i) is ______ $\times 10^{-1}$.
Answer: 16
Solution
The reaction is given as $\mathrm{AB_2} \rightleftharpoons \mathrm{A^{2+}} + 2\mathrm{B^-}$. Initially, the concentrations are $1$, $0$, and $0$. At equilibrium, the concentrations are $1 - \alpha$, $\alpha$, and $2\alpha$. The expression for $i$ is: $$i = 1 + 2\alpha$$ Substituting $\alpha = 0.3$: $$i = 1 + 2 \times (0.3)$$ $$= 1.6$$ $$= 16 \times 10^{-1}$$
Question 75
Chemistry · Alcohols, Phenols and Ethers · Numerical
0.1 mole of compound ' S ' will weigh _______ g. (Given molar mass in g mol$^{-1}$ C : 12, H : 1, O : 16)
Answer: 13
Solution
0.1 mole of compound (S) weight in gm = 0.1 $\times$ molar mass of compound (S) = 0.1 $\times$ 130 = 13 gm