JEE Main 26 June 2022 Shift 1 question paper with solutions
JEE Main 26 June 2022 Shift 1: all 90 questions in paper order (Maths, Physics, Chemistry) with the answer key and worked solutions. Free to read; attempt it as a timed 3-hour mock test.
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Maths
Question 1
Maths · Relations and Functions · Single correct
Let $f(x) = \frac{x-1}{x+1}$, $x \in \mathbb{R} - \{0, -1, 1\}$. If $f^{n+1}(x) = f(f^n(x))$ for all $n \in \mathbb{N}$, then $f^6(6) + f^7(7)$ is equal to:
Maths · Complex Numbers and Quadratic Equations · Single correct
Let $A = \left\{ z \in \mathbb{C} : \left| \frac{z+1}{z-1} \right| < 1 \right\}$ and $B = \left\{ z \in \mathbb{C} : \arg \left( \frac{z-1}{z+1} \right) = \frac{2\pi}{3} \right\}$. Then $A \cap B$ is:
a portion of a circle centred at $\left( 0, -\frac{1}{\sqrt{3}} \right)$ that lies in the second and third quadrants only
a portion of a circle centred at $\left( 0, -\frac{1}{\sqrt{3}} \right)$ that lies in the second quadrant only
an empty set
a portion of a circle of radius $\frac{2}{\sqrt{3}}$ that lies in the third quadrant only
Answer: (b)
Solution
Set A implies $\($ $\left$| $\frac{z+1}{z-1}$ $\right$| < 1 $\)$ which implies $\($ |z+1| < |z-1| $\)$. This leads to $\($ (x+1)^2 + y^2 < (x-1)^2 + y^2 $\)$ which implies $\($ x < 0 $\)$. Set B implies $\($ $\arg$ $\left$( $\frac{z-1}{z+1}$ $\right$) = $\frac{2\pi}{3}$ $\)$. This leads to $\($ $\tan$^{-1} $\left$( $\frac{y}{x-1}$ $\right$) - $\tan$^{-1} $\left$( $\frac{y}{x+1}$ $\right$) = $\frac{2\pi}{3}$ $\)$. This results in $\($ x^2 + y^2 + $\frac{2y}{\sqrt{3}}$ - 1 = 0 $\)$. The intersection $\($ A $\cap$ B $\)$ implies the center is $\($ $\left$( 0, -$\frac{1}{\sqrt{3}}$ $\right$) $\)$.
Question 3
Maths · Matrices · Single correct
Let A be a 3 $\times$ 3 invertible matrix. If $|adj \, (24A)| = adj(3adj(2A))|$, then $|A|^2$ is equal to:
Maths · Continuity and Differentiability · Single correct
Let $f, g : \mathbb{R} \to \mathbb{R}$ be two real valued functions defined as $f(x) = \begin{cases} -|x+3|, & x < 0 \\ e^x, & x \geq 0 \end{cases}$ and $g(x) = \begin{cases} x^2 + k_1 x, & x < 0 \\ 4x + k_2, & x \geq 0 \end{cases}$, where $k_1$ and $k_2$ are real constants. If (gof) is differentiable at $x = 0$, then (gof)(-4) + (gof)(4) is equal to:
Maths · Applications of Derivatives · Single correct
The sum of the absolute minimum and the absolute maximum values of the function $f(x) = |3x - x^2 + 2| - x$ in the interval $[-1, 2]$ is :
$\frac{\sqrt{17} + 3}{2}$
$\frac{\sqrt{17} + 5}{2}$
5
$\frac{9 - \sqrt{17}}{2}$
Answer: (a)
Solution
Given $$f(x) = \begin{cases} x^2 - 4x - 2, & \forall x \in \left(-1, \frac{3 - \sqrt{17}}{2}\right) \\ -x^2 + 2x + 2, & \forall x \in \left(\frac{3 - \sqrt{17}}{2}, 2\right) \end{cases}$$ $f'(x)$ when $x \in \left(-1, \frac{3 - \sqrt{17}}{2}\right)$ $$f'(x) = 2x - 4 = 0 \implies x = 2$$ $$f'(x) = 2(x - 2) \implies f'(x) is always \downarrow$$ $$f(2) = 2$$ $$f(-1) = 3$$ $$f\left(\frac{3 - \sqrt{17}}{2}\right) = \frac{\sqrt{17} - 3}{2}$$ $f'(x)$ when $x \in \left(\frac{3 - \sqrt{17}}{2}, 2\right)$ $$f'(x) = -2x + 2$$ $$f'(x) = -2(x - 1)$$ $$f'(x) = 0 when x = 1$$ $$f(1) = 3$$ absolute minimum value $= \frac{\sqrt{17} - 3}{2}$ absolute maximum value $= 3$ Sum $= \frac{\sqrt{17} - 3}{2} + 3 = \frac{\sqrt{17} + 3}{2}$
Question 9
Maths · Applications of Derivatives · Single correct
Let S be the set of all the natural numbers, for which the line $\frac{x}{a} + \frac{y}{b} = 2$ is a tangent to the curve $$\left( \frac{x}{a} \right)^n + \left( \frac{y}{b} \right)^n = 2$$ at the point $(a, b)$, $ab \neq 0$. Then:
S = $\phi$
n(S) = 1
S = {$2k : k$ $\in$ $\mathbb{N}$\}
S = $\mathbb{N}$
Answer: (d)
Solution
Given $\($ $\left$( $\frac{x}{a}$ $\right$)^n + $\left$( $\frac{y}{b}$ $\right$)^n = 2 $\)$. Slope of tangent at $\($(a, b)$\)$ is calculated as follows: $\[$ n $\left$( $\frac{x}{a}$ $\right$)^{n-1} $\cdot$ $\frac{1}{a}$ + n $\left$( $\frac{y}{b}$ $\right$)^{n-1} $\cdot$ $\frac{1}{b}$ $\frac{dy}{dx}$ = 0 $\]$ $\[$ $\left$. $\frac{dy}{dx}$ $\right$|_{(a,b)} = -$\frac{b}{a}$ $\]$ Therefore, the equation of the tangent is: $\[$ y - b = -$\frac{b}{a}$ (x - a) $\]$ $\[$ $\frac{x}{a}$ + $\frac{y}{b}$ = 2 $\forall$ $\ $n $\in$ $\mathbb{N}$ $\]$
Question 10
Maths · Applications of Integrals · Single correct
The area bounded by the curve $y = |x^2 - 9|$ and the line $y = 3$ is :
Maths · Straight Lines and Pair of Straight Lines · Single correct
Let R be the point (3, 7) and let P and Q be two points on the line x + y = 5 such that PQR is an equilateral triangle. Then the area of $\triangle$ PQR is :
$\frac{25}{4\sqrt{3}}$
$\frac{25\sqrt{3}}{2}$
$\frac{25}{\sqrt{3}}$
$\frac{25}{2\sqrt{3}}$
Answer: (d)
Solution
Given $x + y = 5$ and $\frac{5}{\sqrt{2}}$. We have $\sin 60^\circ = \frac{\frac{5}{\sqrt{2}}}{a}$. Solving for $a$, we get $a = \frac{5\sqrt{2}}{3}$. The area of $\triangle PQR$ is $\frac{\sqrt{3}}{4} a^2 = \frac{25}{2\sqrt{3}}$.
Question 12
Maths · Conic Sections · Single correct
Let C be a circle passing through the points A(2, -1) and B(3, 4). The line segment AB is not a diameter of C. If r is the radius of C and its centre lies on the circle $(x - 5)^2 + (y - 1)^2 = \frac{13}{2}$, then $r^2$ is equal to:
32
$\frac{65}{2}$
$\frac{61}{2}$
30
Answer: (b)
Solution
AB = $\sqrt{26}$. The equation for the radius squared is given by $r^2 = CM^2 + AM^2$. Substituting the values, we have: $$r^2 = \left(2 \times \frac{\sqrt{13}}{2}\right)^2 + \left(\frac{\sqrt{13}}{2}\right)^2$$ Simplifying, we find: $$r^2 = \frac{65}{2}$$
Question 13
Maths · Conic Sections · Single correct
Let the normal at the point P on the parabola $y^2 = 6x$ pass through the point $(5, -8)$. If the tangent at P to the parabola intersects its directrix at the point Q, then the ordinate of the point Q is:
-3
-$\frac{9}{4}$
-$\frac{5}{2}$
-2
Answer: (b)
Solution
Equation of normal: $y = -tx + 2at + at^3$ $\($ $\left$( a = $\frac{3}{2}$ $\right$) $\)$ since passing through $(5, -8)$, we get $t = -2$. Co-ordinate of $Q$: $(6, -6)$. Equation of tangent at $Q$: $x + 2y + 6 = 0$. Put $x = -\frac{3}{2}$ to get $R \left( -\frac{3}{2}, -\frac{9}{4} \right)$.
Question 14
Maths · Three Dimensional Geometry · Single correct
If the two lines $l_1: \frac{x-2}{3} = \frac{y+1}{-2}$, $z = 2$ and $l_2: \frac{x-1}{1} = \frac{2y+3}{\alpha} = \frac{z+5}{2}$ are perpendicular, then an angle between the lines $l_2$ and $l_3: \frac{1-x}{3} = \frac{2y-1}{-4} = \frac{z}{4}$ is:
Maths · Three Dimensional Geometry · Single correct
Let the plane $2x + 3y + z + 20 = 0$ be rotated through a right angle about its line of intersection with the plane $x - 3y + 5z = 8$. If the mirror image of the point $\left(2, -\frac{1}{2}, 2\right)$ in the rotated plane is $B(a, b, c)$, then:
$\frac{a}{8} = \frac{b}{5} = \frac{c}{-4}$
$\frac{a}{4} = \frac{b}{5} = \frac{c}{-2}$
$\frac{a}{8} = \frac{b}{-5} = \frac{c}{4}$
$\frac{a}{4} = \frac{b}{5} = \frac{c}{2}$
Answer: (a)
Solution
Let equation of rotated plane be: $$(2x + 3y + z + 20) + \lambda (x - 3y + 5z - 8) = 0$$ $$(2 + \lambda)x + (3 - 3\lambda)y + (1 + 5\lambda)z + 20 - 8\lambda = 0$$ Above plane is perpendicular to $2x + 3y + z + 20 = 0$. So, $(2 + \lambda) \cdot 2 + (3 - 3\lambda) \cdot 3 + (1 + 5\lambda) \cdot 1 = 0 \Rightarrow \lambda = 7$. Therefore, equation of rotated plane is: $$x - 2y + 4z - 4 = 0$$ Mirror image of $A \left(2, \frac{-1}{2}, 2\right)$ in rotated plane is $B(a, b, c)$. Equation of $AB$: $$\frac{x - 2}{1} = \frac{y + 1/2}{-2} = \frac{z - 2}{4} = k$$ Let coordinate of $B$ be $(2 + k, \frac{-1}{2} - 2k, 2 + 4k)$. Midpoint of $AB$ is: $$\left(2 + \frac{k}{2}, \frac{-1}{2} - k, 2 + 2k\right)$$ which will lie on the plane $x - 2y + 4z - 4 = 0$. Hence $k = \frac{-2}{3}$. Therefore $B$ is: $$\left(\frac{4}{3}, \frac{5}{6}, \frac{-2}{3}\right) \equiv \left(\frac{8}{6}, \frac{5}{6}, \frac{-4}{6}\right)$$ So, $\frac{a}{8} = \frac{b}{5} = \frac{c}{-4}$.
Question 16
Maths · Vector Algebra · Single correct
If $\vec{a} \cdot \vec{b} = 1$, $\vec{b} \cdot \vec{c} = 2$ and $\vec{c} \cdot \vec{a} = 3$, then the value of $$\begin{vmatrix} \vec{a} \times (\vec{b} \times \vec{c}), \vec{b} \times (\vec{c} \times \vec{a}), \vec{c} \times (\vec{b} \times \vec{a}) \end{vmatrix}$$ is:
Let a biased coin be tossed 5 times. If the probability of getting 4 heads is equal to the probability of getting 5 heads, then the probability of getting atmost two heads is:
The mean of the numbers a, b, 8, 5, 10 is 6 and their variance is 6.8. If M is the mean deviation of the numbers about the mean, then 25 M is equal to:
Let $\Delta, \nabla \in \{\land, \lor\}$ be such that $p \nabla q \Rightarrow ((p \nabla q) \nabla r)$ is a tautology. Then $(p \nabla q) \Delta r$ is logically equivalent to:
$(p \Delta r) \lor q$
$(p \Delta r) \land q$
$(p \land r) \Delta q$
$(p \nabla r) \land q$
Answer: (a)
Solution
Case-I If $\Delta \equiv \nabla \equiv \wedge$ then $\left( p \land q \right) \to \left( \left( p \land q \right) \land r \right)$ it can be false if $r$ is false, so not a tautology. Case-II If $\Delta \equiv \nabla \equiv \lor$ then $\left( p \lor q \right) \to \left( \left( p \lor q \right) \lor r \right) \equiv$ tautology then $\left( p \lor q \right) \lor r \equiv \left( p \Delta r \right) \lor q$. Case-III if $\Delta = \lor$, $\nabla = \land$ then $\left( p \land q \right) \to \left\{ \left( p \lor q \right) \land r \right\}$ Not a tautology (Check $p \to T$, $q \to T$, $r \to F$). Case-IV if $\Delta = \land$, $\nabla = \lor$ then $\left( p \land q \right) \to \left\{ \left( p \land q \right) \lor r \right\}$ Not a tautology.
Question 21
Maths · Complex Numbers and Quadratic Equations · Fill in the blank
The sum of the cubes of all the roots of the equation $x^4 - 3x^3 - 2x^2 + 3x + 1 = 10$ is .
Answer: 36
Solution
Given the equation $x^4 - 3x^3 - 2x^2 + 3x + 1 = 10$. Since $x = 0$ is not the root of this equation, divide it by $x^2$. $$x^2 - 3x - 2 + \frac{3}{x} + \frac{1}{x^2} = 0$$ Rewriting, we have: $$x^2 + \frac{1}{x^2} - 2 + 2 - 3 \left( x - \frac{1}{x} \right) - 2 = 0$$ Simplifying further: $$\left( x - \frac{1}{x} \right)^2 - 3 \left( x - \frac{1}{x} \right) = 0$$ Solving for $x$: $$x - \frac{1}{x} = 0, x - \frac{1}{x} = 3$$ For $x - \frac{1}{x} = 0$: $$x^2 - 1 = 0$$ Thus, $x = \pm 1$. For $x - \frac{1}{x} = 3$: $$x^2 - 3x - 1 = 0$$ Let $\alpha = 1$, $\beta = -1$, $\gamma + \delta = 3$, $\gamma \delta = -1$. Calculating $\alpha^3 + \beta^3 + \gamma^3 + \delta^3$: $$1 - 1 + (\gamma + \delta)((\gamma + \delta)^2 - 3\gamma \delta)$$ $$0 + 3(9 - 3(-1))$$ $$+ 3(12) = 36$$
Question 22
Maths · Permutations and Combinations · Numerical
There are ten boys $B_1, B_2, \ldots, B_{10}$ and five girls $G_1, G_2, \ldots, G_5$ in a class. Then the number of ways of forming a group consisting of three boys and three girls, if both $B_1$ and $B_2$ together should not be the members of a group, is
Answer: 1120
Solution
Given $n(B) = 10$ and $n(a) = 5$. The number of ways of forming a group of 3 girls and 3 boys is given by: $$\binom{10}{3} \times \binom{5}{3}$$ Calculating this, we have: $$= \frac{10 \times 9 \times 8}{3 \times 2} \times \frac{5 \times 4}{2} = 1200$$ The number of ways when two particular boys $B_1$ and $B_2$ are members of the group together is: $$\binom{8}{1} \times \binom{5}{3} = 8 \times 10 = 80$$ The number of ways when boys $B_1$ and $B_2$ are in the same group together is: $$= 1200 \times 80 = 1120$$
Question 23
Maths · Conic Sections · Fill in the blank
Let the common tangents to the curves $4(x^2 + y^2) = 9$ and $y^2 = 4x$ intersect at the point $Q$. Let an ellipse, centered at the origin $O$, has lengths of semi-minor and semi-major axes equal to $OQ$ and $6$, respectively. If $e$ and $l$ respectively denote the eccentricity and the length of the latus rectum of this ellipse, then $\frac{l}{e^2}$ is equal to __________.
Answer: d
Solution
Given $x^2 + y^2 = \frac{9}{4}$ and $y = 4x$. The equation of the line is $y = mx + \frac{1}{m}$. Compare equations (1) and (2): $$\pm \frac{3}{2} \sqrt{(1 + m^2)} = \frac{1}{m^2}$$ $$9m^2(1 + m^2) = 4$$ $$9m^4 + 9m^2 - 4 = 0$$ $$9m^4 + 12m^2 - 3m^2 - 4 = 0$$ $$3m^2(3m^2 + 4) - (3m^2 + 4) = 0$$ $$m^2 = -\frac{4}{3} (Rejected)$$ $$m^2 = \frac{1}{3} \implies m = \pm \frac{1}{\sqrt{3}}$$ Equation of common tangent: $$y = \frac{1}{\sqrt{3}} x + \sqrt{3}$$ On the X-axis, $y = 0$. $OQ = -3$ $b = |OQ| = 3$ $a = 6$ $$b^2 = a^2(1 - e^2) \implies e^2 = 1 - \frac{9}{36} = \frac{3}{4}$$ $$e = \frac{2b^2}{a} = \frac{2 \times 9}{6} = 3$$ $$\frac{e}{e^2} = \frac{3}{3/4} = 4$$
Question 24
Maths · Applications of Integrals · Numerical
Let $f(x) = \max\{|x + 1|, |x + 2|, \ldots, |x + 5|\}$. Then $$\int_{-6}^{0} f(x) \, dx$$ is equal to ________.
Answer: 21
Solution
Given $f(x) = \max\{|x+1|, |x+2|, |x+3|, |x+4|, |x+5|\}$. The integral is evaluated as follows: $$\int_{-6}^{0} f(x) \, dx = \int_{-6}^{-3} |x+1| \, dx + \int_{-3}^{0} |x+5| \, dx$$ This simplifies to: $$= -\int_{-6}^{-3} (x+1) \, dx + \int_{-3}^{0} (x+5) \, dx$$ Evaluating the integrals: $$= -\left[ \frac{x^2}{2} + x \right]_{-6}^{-3} + \left[ \frac{x^2}{2} + 5x \right]_{-3}^{0}$$ Substituting the limits: $$= -\left( \frac{9}{2} - 3 \right) - (18 - 6) + \left( 0 - \left( \frac{9}{2} - 15 \right) \right)$$ Simplifying further: $$= -\left[ \frac{3}{2} - 12 \right] + \frac{21}{2} = \frac{21}{2} + \frac{21}{2} = 21$$
Question 25
Maths · Differential Equations · Numerical
Let the solution curve $y = y(x)$ of the differential equation $(4 + x^2)dy - 2x(x^2 + 3y + 4)dx = 0$ pass through the origin. Then $y(2)$ is equal to _______.
Answer: 12
Solution
Given the differential equation $(4 + x^2) dy - 2x(x^2 + 3y + 4) dx$. Rewriting, we have: $$(x^2 + 4) \frac{dy}{dx} = 2x^3 + 6xy + 8x$$ $$(x^2 + 4) \frac{dy}{dx} - 6xy = 2x^3 + 8x$$ This can be written as: $$\frac{dy}{dx} - \frac{6x}{x^2 + 4} y = \frac{2x^3 + 8x}{x^2 + 4}$$ This is a linear differential equation of the form $\frac{dy}{dx} + py = \phi$. The integrating factor is given by: $$e^{\log_e(x^2 + 4)^{-3}} = \frac{1}{(x^2 + 4)^3}$$ Solution: Multiply through by the integrating factor: $$\frac{1}{(x^2 + 4)^3} y = \int \frac{2x^3 + 8x}{(x^2 + 4)^3} (x^2 + 4) \, dx$$ Simplifying, we have: $$\frac{y}{(x^2 + 4)^3} = \int \frac{2x(x^2 + 4)}{(x^2 + 4)^3} \, dx$$ Let $x^2 + 4 = t$, then $2x \, dx = dt$. Thus, $$\frac{y}{(x^2 + 4)^3} = \int \frac{dt}{t^3}$$ Integrating, we get: $$\frac{y}{(x^2 + 4)^3} = \frac{-1}{2(x^2 + 4)^2} + C$$ Since the curve passes through the origin $(0, 0)$, $$0 = \frac{-1}{2 \times 16} + C$$ Solving for $C$, $$C = \frac{1}{32}$$ Thus, $$\frac{y}{(x^2 + 4)^3} = \frac{-1}{2(x^2 + 4)^2} + \frac{1}{32}$$ Simplifying, $$y = \frac{-(x^2 + 4)}{2} + \frac{(x^2 + 4)^3}{32}$$ Evaluating at $x = 2$, $$y(2) = -8 + \frac{8 \times 8 \times 8}{32}$$ $$y(2) = -8 + 16 = 8$$
Question 26
Maths · Trigonometric Functions · Numerical
If $\sin^2(10^\circ) \sin(20^\circ) \sin(40^\circ) \sin(50^\circ) \sin(70^\circ) = \alpha - \frac{1}{16} \sin(10^\circ)$, then $16 + \alpha^{-1}$ is equal to .
Let A = $\{$ n $\in$ $\mathbb{N}$ : $\mathrm{H.C.F.}$ (n, 45) = 1 $\}$ and Let B = $\{$ 2k : k $\in$ $\{$ 1, 2, ..., 100 $\}$ $\}$. Then the sum of all the elements of A $\cap$ B is ________.
Answer: 5264
Solution
Sum of elements in $A \cap B$ $$= (2 + 4 + 6 + \ldots + 200) - (6 + 12 + \ldots + 198)$$ Multiple of 2, Multiple of 2 $\&$ 3 i.e. 6 $$- (10 + 20 + \ldots + 200) + (30 + 60 + \ldots + 180)$$ Multiple of 5 $\&$ 2 i.e. 10, Multiple of 2, 5 $\&$ 3 i.e. 30 $$= 5264$$
Question 28
Maths · Integrals · Numerical
The value of the integral $$\frac{48}{\pi^4} \int_{0}^{\pi} \left( \frac{3\pi x^2}{2} - x^3 \right) \frac{\sin x}{1 + \cos^2 x} \, dx$$ is equal to ________.
Let $S = (0, 2\pi) - \left\{ \frac{\pi}{2}, \frac{3\pi}{4}, \frac{3\pi}{2}, \frac{7\pi}{4} \right\}$. Let $y = y(x)$, $x \in S$, be the solution curve of the differential equation $\frac{dy}{dx} = \frac{1}{1 + \sin 2x}$, $y\left(\frac{\pi}{4}\right) = \frac{1}{2}$. If the sum of abscissas of all the points of intersection of the curve $y = y(x)$ with the curve $y = \sqrt{2} \sin x$ is $\frac{k\pi}{12}$, then $k$ is equal to .
Answer: 42
Solution
Given $\($ $\frac{dy}{dx}$ = $\frac{1}{1 + \sin 2x}$ $\)$. Integrating both sides, we have: $$ y(x) = -\frac{1}{1 + \tan x} + C $$ Given $\($ y$\left$( $\frac{\pi}{4}$ $\right$) = $\frac{1}{2}$ = -$\frac{1}{2}$ + C $\)$, we find $\($ C = 1 $\)$. Thus, $$ y(x) = \frac{-1}{1 + \tan x} + 1 $$ Simplifying, $$ y(x) = \frac{-1 + 1 + \tan x}{1 + \tan x} $$ $$ y(x) = \frac{\tan x}{1 + \tan x} $$ Solving with $\($ y = $\sqrt{2}$ $\sin$ x $\)$, $$ \frac{\tan x}{1 + \tan x} = \sqrt{2} \sin x $$ For $\($ $\sin$ x = 0 $\)$, $\($ $\frac{1}{\sqrt{2}}$ = $\sin$ x + $\cos$ x $\)$. Thus, $\($ x = $\pi$ $\)$ and $\($ $\frac{1}{2}$ = $\sin$ $\left$( x + $\frac{\pi}{4}$ $\right$) $\)$. Also, $\($ $\sin$ $\frac{\pi}{6}$ = $\sin$ $\left$( x + $\frac{\pi}{4}$ $\right$) $\)$. Therefore, $$ x + \frac{\pi}{4} = \pi - \frac{\pi}{6}, 2\pi + \frac{\pi}{6} $$ The sum of solutions is: $$ x = \frac{5\pi}{12}, \frac{13\pi}{12} - \frac{\pi}{12} $$ Thus, $$ = \pi + \frac{7\pi}{12} + \frac{23\pi}{12} $$ $$ = \frac{12\pi + 7\pi + 23}{12} = \frac{42\pi}{12} = \frac{k\pi}{12} $$ Therefore, $\($ k = 42 $\)$.
Physics
Question 31
Physics · Physical World, Units and Measurements · Single correct
An expression for a dimensionless quantity P is given by $P = \frac{\alpha}{\beta} \log_e \left( \frac{kt}{\beta x} \right)$; where $\alpha$ and $\beta$ are constants, $x$ is distance; $k$ is Boltzmann constant and $t$ is the temperature. Then the dimensions of $\alpha$ will be:
Physics · Motion in a Straight Line · Single correct
A person is standing in an elevator. In which situation, he experiences weight loss?
When the elevator moves upward with constant acceleration
When the elevator moves downward with constant acceleration
When the elevator moves upward with uniform velocity
When the elevator moves downward with uniform velocity
Answer: (b)
Solution
Given the forces acting on the person in the lift, we have: $$mg - N = ma$$ Solving for $N$, we get: $$N = m(g - a)$$ Therefore, the person experiences weight loss when the acceleration of the lift is downward.
Question 33
Physics · Motion in a Straight Line · Single correct
An object is thrown vertically upwards. At its maximum height, which of the following quantity becomes zero?
Momentum
Potential energy
Acceleration
Force
Answer: (a)
Solution
At maximum height, $V = 0$. Therefore, the momentum of the object is zero.
Question 34
Physics · Laws of Motion · Single correct
A ball is released from rest from point P of a smooth semi-spherical vessel as shown in figure. The ratio of the centripetal force and normal reaction on the ball at point Q is A while angular position of point Q is $\alpha$ with respect to point P. Which of the following graphs represent the correct relation between A and $\alpha$ when ball goes from Q to R?
Physics · System of Particles and Rotational Motion · Single correct
A thin circular ring of mass M and radius R is rotating with a constant angular velocity 2 rads$^{-1}$ in a horizontal plane about an axis vertical to its plane and passing through the center of the ring. If two objects each of mass m be attached gently to the opposite ends of a diameter of ring, the ring will then rotate with an angular velocity (in rads$^{-1}$).
The variation of acceleration due to gravity ($g$) with distance ($r$) from the center of the earth is correctly represented by: (Given $R =$ radius of earth)
Answer: (a)
Solution
The gravitational field strength $g$ is given by the piecewise function: $$g = \begin{cases} \frac{GMr}{R^3}, & r \leq R \\ \frac{GM}{r^2}, & r \geq R \end{cases}$$ The graph shows $g$ as a function of $r$, with a linear increase up to $R$ and a decrease following an inverse square law beyond $R$.
Question 37
Physics · Thermodynamics · Single correct
The efficiency of a Carnot's engine, working between steam point and ice point, will be:
26.81$\%$
37.81$\%$
47.81$\%$
57.81$\%$
Answer: (c)
Solution
The period is given by the formula $$T = 2\pi \sqrt{\frac{\ell}{g_{eff}}}$$. (a) When $a = 0$, the period is $$T = 2\pi \sqrt{\frac{\ell}{g}}$$. (b) When $a = \frac{g}{6}$, the period is $$T' = 2\pi \sqrt{\frac{\ell}{g + \frac{g}{6}}}$$. Therefore, $$T' = \sqrt{\frac{6}{7}} T$$.
Question 38
Physics · Oscillations · Single correct
Time period of a simple pendulum in a stationary lift is $T$. If the lift accelerates with $\frac{g}{6}$ vertically upwards then the time period will be : (where $g =$ acceleration due to gravity)
$\sqrt{\frac{6}{5}} T$
$\sqrt{\frac{5}{6}} T$
$\sqrt{\frac{6}{7}} T$
$\sqrt{\frac{7}{6}} T$
Answer: (c)
Solution
Question 39
Physics · Thermodynamics · Single correct
A thermally insulated vessel contains an ideal gas of molecular mass $M$ and ratio of specific heats 1.4. Vessel is moving with speed $v$ and is suddenly brought to rest. Assuming no heat is lost to the surrounding and vessel temperature of the gas increases by : (R = universal gas constant)
$\frac{Mv^2}{7R}$
$\frac{Mv^2}{5R}$
$\frac{2Mv^2}{7R}$
$\frac{7Mv^2}{5R}$
Answer: (b)
Solution
Question 40
Physics · Electrostatic Potential and Capacitance · Single correct
Two capacitors having capacitance $C_1$ and $C_2$ respectively are connected as shown in figure. Initially, capacitor $C_1$ is charged to a potential difference $V$ volt by a battery. The battery is then removed and the charged capacitor $C_1$ is now connected to uncharged capacitor $C_2$ by closing the switch $S$. The amount of charge on the capacitor $C_2$, after equilibrium is:
Assertion (A) : Non-polar materials do not have any permanent dipole moment. Reason (R) : When a non-polar material is placed in an electric field, the centre of the positive charge distribution of its individual atom or molecule coincides with the centre of the negative charge distribution. In the light of above statements, choose the most appropriate answer from the options given below.
Both (A) and (R) are correct and (R) is the correct explanation of (A).
Both (A) and (R) are correct and (R) is not the correct explanation of (A).
is correct but (R) is not correct.
is not correct but (R) is correct.
Answer: (c)
Solution
S1: In nonpolar molecules, centre of positive charge coincides with centre of negative charge, hence net dipole moment comes to zero. S2: When nonpolar material is placed in external field, centre of charges does not coincide, hence gives non-zero moment in field.
Question 42
Physics · Electromagnetic Induction · Single correct
The magnetic flux through a coil perpendicular to its plane is varying according to the relation $\phi = (5t^3 + 4t + 2t - 5)$ Weber. If the resistant of the coil is $5 \, \mathrm{ohm}$, then the induced current through the coil at $t = 2 \, \mathrm{sec}$ will be:
15.6 A
16.6 A
17.6 A
18.6 A
Answer: (a)
Solution
Given $\phi = 5t^3 + 4t^2 + 2t - 5$. The magnitude of $e$ is given by $\left| e \right| = \left| \frac{d\phi}{dt} \right| = 15t^2 + 8t + 2$. At $t = 2$, $\left| e \right| = 15 \times 2^2 + 8 \times 2 + 2$. Therefore, $e = 78 \, \mathrm{V}$ implies $I = \frac{e}{R} = \frac{78}{5} = 15.60$.
Question 43
Physics · Current Electricity · Single correct
An aluminium wire is stretched to make its length, 04$\%$ larger. Then percentage change in resistance is:
0.4 $\%$
0.2 $\%$
0.8 $\%$
0.6 $\%$
Answer: (c)
Solution
Given the formula for resistance, $$R = \frac{\rho \ell}{A}$$ we have the relative change in resistance as $$\frac{\Delta R}{R} = \frac{\Delta \ell}{\ell} - \frac{\Delta A}{A}$$ Given that $$\ell A = k$$ we have $$\frac{\Delta \ell}{\ell} + \frac{\Delta A}{A} = 0$$ Therefore, $$\frac{\Delta R}{R} = \frac{2 \Delta \ell}{\ell}$$ Substituting the given values, $$\frac{\Delta R}{R} = 2 \times 0.4 = 0.8\%$$
Question 44
Physics · Moving Charges and Magnetism · Single correct
A proton and an alpha particle of the same enter in a uniform magnetic field which is acting perpendicular to their direction of motion. The ratio of the circular paths described by the alpha particle and proton is:
If electric field intensity of a uniform plane electro magnetic wave is given as $$\mathbf{E} = -301.6 \sin(kz - \omega t) \hat{a}_x + 452.4 \sin(kz - \omega t) \hat{a}_y \frac{\mathrm{V}}{\mathrm{m}}$$ Then, magnetic intensity $\mathbf{H}$ of this wave in $\mathrm{Am}^{-1}$ will be: [Given: Speed of light in vacuum $c = 3 \times 10^8 \, \mathrm{ms}^{-1}$, permeability of vacuum $\mu_0 = 4\pi \times 10^{-7} \, \mathrm{NA}^{-2}$]
In free space, an electromagnetic wave of 3 GHz of 3 GHz frequency strikes over the edge of an object of size $\frac{\lambda}{100}$, where $\lambda$ is the wavelength of the wave in free space. The phenomenon, which happens there will be:
Reflection
Refraction
Diffraction
Scattering
Answer: (d)
Solution
For reflection, size of obstacle must be much larger than wavelength, for diffraction size should be order of wavelength. Since the object is of size $\frac{\lambda}{100}$, much smaller than wavelength, so scattering will occur.
Question 47
Physics · Dual Nature of Radiation and Matter · Single correct
An electron with speed $v$ and a photon with speed $c$ have the same de-Broglie wavelength. If the kinetic energy and momentum of electron are $E_e$ and $p_e$ and that of photon are $E_{ph}$ and $p_{ph}$ respectively. Which of the following is correct?
How many alpha and beta particles are emitted when Uranium $_{92}^{238}\mathrm{U}$ decays to lead $_{82}^{206}\mathrm{Pb}$?
3 alpha particles and 5 beta particles
6 alpha particles and 4 beta particles
4 alpha particles and 5 beta particles
8 alpha particles and 6 beta particles
Answer: (d)
Solution
The reaction is given by: $$^{238}_{92} \mathrm{U} \rightarrow \boxed{8} \; ^{4}_{2} \mathrm{He} + \boxed{6} \; ^{0}_{-1} \mathrm{e} + ^{206}_{82} \mathrm{Pb}$$ 8 $\alpha$ particles and 6 $\beta$ particles are emitted.
Question 49
Physics · Semiconductor Electronics: Materials, Devices and Simple Circuits · Single correct
The I-V characteristics of a p-n junction diode in forward bias is shown in the figure. The ratio of dynamic resistance, corresponding to forward bias voltages of 2V and 4V respectively, is:
1 : 2
5 : 1
1 : 40
20 : 1
Answer: (b)
Solution
Given the formula for resistance, $R = \frac{\Delta V}{\Delta i}$. We have: $$\frac{R_1}{R_2} = \frac{\Delta v_1}{\Delta v_2} \frac{\Delta i_2}{\Delta i_1} = \frac{0.1}{0.2} \times \frac{50}{5} = 5$$
Question 50
Physics · Communication Systems · Single correct
Choose the correct statement for amplitude modulation:
Amplitude of modulating is varied in accordance with the information signal.
Amplitude of modulated is varied in accordance with the information signal.
Amplitude of carrier signal is varied in accordance with the information signal.
Amplitude of modulated is varied in accordance with the modulating signal.
Answer: (c)
Solution
In amplitude modulation, the amplitude of high frequency carrier wave is varied in accordance with message signal.
Question 51
Physics · Motion in a Plane · Numerical
A fighter jet is flying horizontally at a certain altitude with a speed of $200 \, \mathrm{m/s}$. When it passes directly overhead an anti-aircraft gun, bullet is fired from the gun, at an angle $\theta$ with the horizontal, to hit the jet. If the bullet speed is $400 \, \mathrm{m/s}$, the value of $\theta$ will be .......... $^\circ$.
Answer: 60
Solution
Both should have same horizontal component of velocity. $$200 = 400 \cos \theta$$ $$\theta = 60^\circ$$
Question 52
Physics · Motion in a Straight Line · Numerical
A ball of mass $0.5 \, \mathrm{kg}$ is dropped from the height of $10 \, \mathrm{m}$. The height, at which the magnitude of velocity becomes equal to the magnitude of acceleration due to gravity, is .............. m. (Use $g = 10 \, \mathrm{m/s^2}$).
Physics · Mechanical Properties of Solids · Numerical
The elastic behaviour of material for linear stress and linear strain, is shown in the figure. The energy density for a linear strain of $5 \times 10^{-4}$ is ............ $\mathrm{kJ/m^3}$. Assume that material is elastic upto the linear strain of $5 \times 10^{-4}$.
Answer: 25
Solution
Given $\($ y = $\frac{stress}{strain}$ = 2.0 $\times$ 10^{10} $\)$. Energy density = $\($ $\frac{1}{2}$ stress $\times$ strain $\)$ $\[$ = $\frac{1}{2}$ (strain)^2 $\cdot$ y = $\frac{1}{2}$ (5 $\times$ 10^{-4})^2 $\times$ 20 $\times$ 10^{10} $\]$ $\[$ = 25 $\times$ 10^2 $\times$ 10 = 25 $\frac{kJ}{m^3}$ $\]$ Ans. 25
Question 54
Physics · Gravitation · Numerical
The elongation of a wire on the surface of the earth is $10^{-4} \, \mathrm{m}$. The same wire of same dimensions is elongated by $6 \times 10^{-5} \, \mathrm{m}$ on another planet. The acceleration due to gravity on the planet will be ............ $\mathrm{ms^{-2}}$. (Take acceleration due to gravity on the surface of earth = $10 \, \mathrm{m/s^{2}}$)
A $10\,\Omega$, $20\,\mathrm{mH}$ coil carrying constant current is connected to a battery of $20\,\mathrm{V}$ through a switch is opened current becomes zero in $100\mu\mathrm{s}$. The average emf induced in the coil is $\ldots$ V.
Answer: 400
Solution
Question 56
Physics · Ray Optics and Optical Instruments · Numerical
A light ray is incident, at an incident angle $\theta_1$, on the system of two plane mirrors $M_1$ and $M_2$ having an inclination angle $75^\circ$ between them (as shown in figure). After reflecting from mirror $M_1$ it gets reflected back by the mirror $M_2$ with an angle of reflection $30^\circ$. The total deviation of the ray will be ............. degree.
Answer: 210
Solution
Given $\delta_{total} = 360^\circ - 2\theta$. $$= 360^\circ - 2 \times 75^\circ$$ $$\delta_{total} = 210^\circ$$ From the diagram, $\theta_1 = 45^\circ$. In the second diagram, $\delta = 120^\circ + 90^\circ = 210^\circ$.
Question 57
Physics · Experimental Physics · Numerical
In a vernier callipers, each cm on the main scale is divided into 20 equal parts. If tenth vernier scale division coincides with nineth main scale division. Then the value of vernier constant will be ............. $\times 10^{-2} \, \mathrm{mm}$.
Answer: 5
Solution
20 MSD = 1 cm 1 MSD = $\frac{1}{20}$ cm 10 VSD = 9 MSD 1 VSD = $\frac{9}{10}$ MSD = $\frac{9}{10}$ $\times$ $\frac{1}{20}$ cm 1 VSD = $\frac{9}{200}$ cm VC = 1 MSD - 1 VSD = $\frac{1}{20}$ cm - $\frac{9}{200}$ cm = $\frac{1}{200}$ $\times$ 10 mm VC = 5 $\times$ 10^{-2} mm Ans. 5
As per the given circuit, the value of current through the battery will be .......... A.
Answer: 1
Solution
Given $V = IR_{net}$. $$10 = I \times 10$$ Therefore, $I = 1 \, \mathrm{A}$. Ans. 1
Question 59
Physics · Alternating Current · Numerical
A 110 V , 50 Hz, AC source is connected in the circuit (as shown in figure). The current through the resistance 55 Ω, at resonance in the circuit, will be .............. A.
Answer: 0
Solution
At resonance $I_L = I_C$. Alternatively, $$\frac{1}{Z} = \sqrt{\left(\frac{1}{X_L} - \frac{1}{X_C}\right)^2}$$ At resonance, $X_L = X_C$ and $Z \to \infty$. Therefore, $Z_{total circuit} \to \infty$, i.e., $I = 0$. Ans. 0
Question 60
Physics · Mechanical Properties of Fluids · Numerical
An ideal fluid of density $800 \, \mathrm{kgm^{-3}}$, flows smoothly through a bent pipe (as shown in figure) that tapers in cross-sectional area from $a$ to $\frac{a}{2}$. The pressure difference between the wide and narrow sections of pipe is $4100 \, \mathrm{Pa}$. At wider section, the velocity of fluid is $\frac{\sqrt{x}}{6} \, \mathrm{ms^{-1}}$ for $x = \ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots$. (Given $g = 10 \, \mathrm{m^{2}}$)
Chemistry · Some Basic Concepts of Chemistry · Single correct
A commercially sold conc. HCl is 35$\%$ HCl by mass. If the density of this commercial acid is 1.46 $\mathrm{g/mL}$, the molarity of this solution is : (Atomic mass : $\mathrm{Cl}$ = 35.5 $\mathrm{amu}$, $\mathrm{H}$ = 1 $\mathrm{amu}$)
10.2 $\mathrm{M}$
12.5 $\mathrm{M}$
14.0 $\mathrm{M}$
18.2 $\mathrm{M}$
Answer: (c)
Solution
Let total volume = 1000 $\mathrm{mL}$ = 1 $\mathrm{L}$. Total mass of solution = 1460 $\mathrm{g}$. Mass of $\mathrm{HCl}$ = $\frac{35}{100}$ $\times$ 1460. Moles of $\mathrm{HCl}$ = $\frac{35 \times 1460}{100 \times 36.5}$. So molarity = $\frac{35 \times 1460}{100 \times 36.5}$ = 14 $\mathrm{M}$.
Question 62
Chemistry · States of Matter · Single correct
An evacuated glass vessel weighs 40.0 $\mathrm{g}$ when empty, 135.0 $\mathrm{g}$ when filled with a liquid of density 0.95 $\mathrm{g}$ \, $\mathrm{mL}^{-1}$ and 40.5 $\mathrm{g}$ when filled with an ideal gas at 0.82 $\mathrm{atm}$ at 250 $\mathrm{K}$. The molar mass of the gas in $\mathrm{g}$ \, $\mathrm{mol}^{-1}$ is: (Given : R = 0.082 \, $\mathrm{L}$ \, $\mathrm{atm}$ \, $\mathrm{K}^{-1}$ \, $\mathrm{mol}^{-1}$)
35
50
75
125
Answer: (d)
Solution
Mass of liquid $=135-40=95\,\mathrm{g}$ Volume of liquid $=\frac{\text{mass}}{\text{density}}=\frac{95}{0.95}\,\mathrm{mL}=100\,\mathrm{mL}=0.1\,\mathrm{L}$ Mass of ideal gas $=40.5-40\,\mathrm{g}=0.5\,\mathrm{g}$ $PV=nRT$ $0.82\times0.1=\left(\frac{0.5}{M}\right)\times0.082\times250$ $M=125$
Question 63
Chemistry · Structure of Atom · Single correct
If the radius of the 3rd Bohr's orbit of hydrogen atom is $r_3$ and the radius of 4th Bohr's orbit is $r_4$. Then:
$r_4 = \frac{9}{16} r_3$
$r_4 = \frac{16}{9} r_3$
$r_4 = \frac{3}{4} r_3$
$r_4 = \frac{4}{3} r_3$
Answer: (b)
Solution
Given the formula for the radius: $$r = 0.529 \times \frac{n^2}{z} \, Å$$ Calculate $r_3$: $$r_3 = 0.529 \times \frac{3^2}{1}$$ Calculate $r_4$: $$r_4 = 0.529 \times \frac{4^2}{1}$$ The ratio $\frac{r_4}{r_3}$ is: $$\frac{r_4}{r_3} = \frac{4^2}{3^2} = \frac{16}{9}$$ Thus, $$r_4 = \frac{16r_3}{9}$$
Question 64
Chemistry · Chemical Bonding and Molecular Structure · Single correct
Consider the ions/molecule $O_2^+$, $O_2$, $O_2^-$, $O_2^{2-}$ For increasing bond order the correct option is:
$O_2^{2-} < O_2^- < O_2 < O_2^+$
$O_2^- < O_2^{2-} < O_2 < O_2^+$
$O_2^- < O_2^{2-} < O_2^+ < O_2
$O_2^- < O_2^+ < O_2^{2-} < O_2
Answer: (a)
Solution
\begin{tabular}{|l|c|c|c|} \hline \textbf{ion/molecule} & \textbf{Number of $e^-$ in BMO} & \textbf{Number of $e^-$ in ABMO} & \textbf{Bond order} \\ \hline O$_2^+$ & 10 & 5 & 2.5 \\ \hline O$_2$ & 10 & 6 & 2 \\ \hline O$_2^-$ & 10 & 7 & 1.5 \\ \hline O$_2^{2-}$ & 10 & 8 & 1 \\ \hline \end{tabular} Bond order $O_2^{2-}<O_2^-<O_2<O_2^+$
Question 65
Chemistry · Electrochemistry · Single correct
The $\left(\frac{\partial E}{\partial T}\right)_P$ values of different types of half-cells are as follows: A: $1\times10^{-4}$ B: $2\times10^{-4}$ C: $0.1\times10^{-4}$ D: $0.2\times10^{-4}$ (Where $E$ is the electromotive force.) Which of the above half-cells would be preferred for use as a reference electrode?
A
B
C
D
Answer: (c)
Solution
A cell with less variation in EMF with temperature is preferred as a reference electrode because it can be used over a wider temperature range without much deviation from its standard value. Therefore, a cell with a smaller value of $\left(\frac{\partial E}{\partial T}\right)_P$ is preferred.
Question 66
Chemistry · The p-Block Elements (Group-13 and 14) · Single correct
Choose the correct stability order of group 13 elements in their +1 oxidation state.
Al < Ga < In < Tl
Tl < In < Ga < Al
Al < Ga < Tl < In
Al < Tl < Ga < In
Answer: (a)
Solution
Moving down the group, stability of lower oxidation state increases. $$\mathrm{Al} < \mathrm{Ga} < \mathrm{In} < \mathrm{Tl}$$
Question 67
Chemistry · General Principles and Processes of Isolation of Elements · Single correct
Given below are two statements : Statement I : According to the Ellingham diagram, any metal oxide with higher $\Delta G^\circ$ is more stable than the one with lower $\Delta G^\circ$. Statement II : The metal involved in the formation of oxide placed lower in the Ellingham diagram can reduce the oxide of a metal placed higher in the diagram. In the light of the above statements, choose the most appropriate answer from the options given below :
Both Statement I and Statement II are correct.
Both Statement I and Statement II are incorrect.
Statement I is correct but Statement II is incorrect.
Statement I is incorrect but Statement II is correct.
Answer: (d)
Solution
Metal oxide with lower $\Delta G^\circ$ is more stable. Statement II is correct.
Question 68
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct
Consider the following reaction: $$2\mathrm{HSO}_4^- (\mathrm{aq}) \xrightarrow{(1) Electrolysis \atop (2) Hydrolysis} 2\mathrm{HSO}_4^- + 2\mathrm{H}^+ + \mathrm{A}$$ The dihedral angle in product A in its solid phase at 110 K is:
$104^\circ$
$111.5^\circ$
$90.2^\circ$
$111.0^\circ$
Answer: (c)
Solution
The reaction involves electrolysis and hydrolysis of $2\mathrm{HSO_4^- (aq.)}$ to form $2\mathrm{HSO_4^-} + 2\mathrm{H^+} + \mathrm{H_2O_2}$. The structure shown is a solid phase with an angle of $90.2^\circ$.
Question 69
Chemistry · The s-Block Elements · Single correct
The correct order of melting point is :
Be > Mg > Ca > Sr
Sr > Ca > Mg > Be
Be > Ca > Mg > Sr
Be > Ca > Sr > Mg
Answer: (d)
Solution
The melting points (M.P) of the elements are given as follows: Beryllium (Be): $1560 \, \mathrm{K}$ Magnesium (Mg): $924 \, \mathrm{K}$ Calcium (Ca): $1124 \, \mathrm{K}$ Strontium (Sr): $1062 \, \mathrm{K}$
Question 70
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct
The correct order of melting points of hydrides of group 16 elements is :
H_2S < H_2Se < H_2Te < H_2O
H_2O < H_2S < H_2Se < H_2Te
H_2S < H_2Te < H_2Se < H_2O
H_2Se < H_2S < H_2Te < H_2O
Answer: (a)
Solution
\begin{tabular}{|l|c|} \hline \textbf{Hydride} & \textbf{M.P.} \\ \hline H$_2$O & 273 K \\ \hline H$_2$S & 188 K \\ \hline H$_2$Se & 208 K \\ \hline H$_2$Te & 222 K \\ \hline \end{tabular}
Question 71
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct
Consider the following reaction: A + alkali $\rightarrow$ B (Major Product) If B is an oxoacid of phosphorus with no P–H bond, then A is:
White $P_4$
Red $P_4$
$P_2O_3$
$H_3PO_3$
Answer: (b)
Solution
White $\mathrm{P_4}$ + alkali $\rightarrow \mathrm{H_3PO_2}$ Red $\mathrm{P_4}$ + alkali $\rightarrow \mathrm{H_4P_2O_6}$
Question 72
Chemistry · The p-Block Elements (Group 15, 16, 17 & 18) · Single correct
Polar stratospheric clouds facilitate the formation of:
ClONO_2
HOCl
ClO
CH_4
Answer: (b)
Solution
Polar stratospheric clouds provide surface on which hydrolysis of $\mathrm{ClONO_2}$ takes place to form $\mathrm{HOCl}$ (Hypochlorous acid). $$\mathrm{ClONO_2(g) + H_2O(g) \rightarrow HOCl(g) + HNO_3(g)}$$
Question 73
Chemistry · Organic Chemistry — Some Basic Principles & Techniques · Single correct
Given below are two statements : Statement I : In 'Lassaigne's Test, when both nitrogen and sulphur are present in an organic compound, sodium thiocyanate is formed. Statement II : If both nitrogen and sulphur are present in an organic compound, then the excess of sodium used in sodium fusion will decompose the sodium thiocyanate formed to give NaCN and $Na_2S$. In the light of the above statements, choose the most appropriate answer from the options given below :
Both Statement I and Statement II are correct.
Both Statement I and Statement II are incorrect.
Statement I is correct but Statement II is incorrect.
Statement I is incorrect but Statement II is correct.
Answer: (a)
Solution
Both statement I and statement II are correct.
Question 74
Chemistry · Alcohols, Phenols and Ethers · Single correct
$(C_7H_5O_2)_2$ $\xrightarrow{h\nu}$ $[X]+2\,\overset{\bullet}{C_6H_5}+2CO_2$ Consider the above reaction and identify the intermediate 'X'
C_6H_5-$\overset{\oplus}{\mathrm{C}}$=O
C_6H_5-$\overset{\ominus}{\mathrm{C}}$=O
Answer: (d)
Solution
The reaction involves the photochemical decomposition of a peroxide compound. Upon exposure to light $h\nu$, the peroxide bond breaks, leading to the formation of a phenyl radical and a benzoate radical. The benzoate radical further decomposes to form a phenyl radical and carbon dioxide $\mathrm{CO_2}$. The overall reaction results in the formation of two phenyl radicals and the release of $\mathrm{CO_2}$.
Question 75
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
Consider the above reaction sequence and identify the product $\textbf{B}$.
Answer: (a)
Solution
Although Acetyl Acetone predominantly gives Acid base reaction with G.R due to Active methylene group but according to given option ans should be based on nucleophilic addition reaction (NAR).
Question 76
Chemistry · Aldehydes, Ketones and Carboxylic Acids · Single correct
Which will have the highest enol content?
Answer: (c)
Solution
The compound on the left is a tautomer of the compound on the right, which is aromatic in nature.
Question 77
Chemistry · Amines · Single correct
Among the following structures, which will show the most stable enamine formation? (Where Me is $-\mathrm{CH}_3$)
Answer: (c)
Solution
All these enamines are interconvertible through their resonating structures. So most stable form is 'C' due to steric factor.
Question 78
Chemistry · Polymers · Single correct
Which of the following sets are correct regarding polymer ? (A) Copolymer : Buna–S (B) Condensation polymer : Nylon–6,6 (C) Fibre : Nylon–6,6 (D) Thermosetting polymer : Terylene (E) Homopolymer : Buna–N Choose the correct answer from given options below:
(A), (B) and ( C ) are correct
(B), ( C ) and (D) are correct
(A), ( C ) and (E) are correct
(A), (B) and (D) are correct
Answer: (a)
Solution
Which of the following set are correct regarding polymer. Bona - 5 is copolymer of butadiene + styrene Nylon 6.6 is condensation polymer of adipic Acid and hexanediamine. Nylon 6.6 is fiber Terylene is fiber not thermosetting polymer Buna-N is copolymer not Homopolymer
Question 79
Chemistry · Chemistry in Everyday Life · Single correct
A chemical which stimulates the secretion of pepsin is :
Anti histamine
Cimetidine
Histamine
Zantac
Answer: (c)
Solution
Histamine (It is used for secretion of pepsin & HCl in stomach)
Question 80
Chemistry · Co-ordination Compounds · Single correct
Which statement is not true with respect to nitrate ion test?
A dark brown ring is formed at the junction of two solutions.
Ring is formed due to nitroferrous sulphate complex.
The brown complex is $[\mathrm{Fe(H_2O)_5(NO)]SO_4}$.
Heating the nitrate salt with conc. $\mathrm{H_2SO_4}$, light brown fumes are evolved.
Answer: (b)
Solution
Ring is formed due to formation of nitrosoferrous sulphate.
Question 81
Chemistry · Thermodynamics · Numerical
For complete combustion of methanol $\mathrm{CH_3OH}(l)$+$\frac{3}{2}\mathrm{O_2}(g)$ $\rightarrow$ $\mathrm{CO_2}(g)$+$2\mathrm{H_2O}(l)$ the amount of heat produced as measured by bomb calorimeter is $726\ \mathrm{kJ\ mol^{-1}}$ at $27^\circ\mathrm{C}$. The enthalpy of combustion for the reaction is $-x\ \mathrm{kJ\ mol^{-1}}$, where $x$ is ________. (Nearest integer) (Given : R=8.3 \mathrm{J}\,$\mathrm{K^{-1}}$\,$\mathrm{mol^{-1}}$)
Answer: 727
Solution
Given $\Delta U = -726 \, \mathrm{KJ/mol}$. $\Delta ng = 1 - 3/2 = -\frac{1}{2}$. $\Delta H = \Delta U + \Delta ng RT$. $$= -726 - \frac{1}{2} \times \frac{8.3 \times 300}{1000}$$ $$= -727.245$$
Question 82
Chemistry · Solutions · Numerical
A 0.5 percent solution of potassium chloride was found to freeze at $-0.24^\circ \mathrm{C}$. The percentage dissociation of potassium chloride is ________. (Nearest integer) (Molal depression constant for water is $1.80 \, \mathrm{K \, kg \, mol^{-1}}$ and molar mass of KCl is $74.6 \, \mathrm{g \, mol^{-1}}$)
Answer: 98
Solution
For a 0.5% solution of KCl, we have: $$\Delta T_f = i \cdot m_f$$ $$0.24 = i \cdot \frac{0.5}{74.6} \times \frac{1.80}{0.1}$$ $$i = \frac{0.24 \times 74.6}{0.5 \times 1.80} \times 0.1$$ $$= 1.989$$ Now, using the equation: $$1.989 = 1 + \alpha (n-1)$$ $$1.989 = 1 + \alpha$$ $$\alpha = 0.989$$ The percentage of $\alpha$ is $98.9\%$. Answer is $99\%$. If the mass of $\mathrm{H_2O} = 99.5$: $$m = \frac{0.5}{74.5} \times \frac{1}{0.0995}$$ $$i = \frac{0.24 \times 74.6 \times 0.0995}{0.5 \times 1.80}$$ $$= 1.979$$ Again, using the equation: $$1.979 = 1 + \alpha (n-1)$$ The percentage of $\alpha$ is $97.9\%$.
Question 83
Chemistry · Equilibrium · Numerical
50 $\mathrm{mL}$ of 0.1$\mathrm{M}$ $CH_3COOH$ is being titrated against 0.1 $\mathrm{M}$ NaOH. When 25 $\mathrm{mL}$ of NaOH has been added, the pH of the solution will be $\times 10^{-2}$. (Nearest integer) (Given : $pK_a (CH_3COOH)$ = 4.76) $\log$ 2 = 0.30
Answer: 476
Solution
Moles of $\mathrm{CH_3COOH} = 5$ m mole. Moles of $\mathrm{NaOH} = 2.5$ m mole. $$\mathrm{NaOH} + \mathrm{CH_3COOH} \longrightarrow \mathrm{CH_3COONa} + \mathrm{H_2O}$$ $2.5$ m mole $2.5$ m mole $0 2.5$ m mole $ 2.5$ m mole So buffer is formed. $$\mathrm{pH} = \mathrm{pKa} + \log \left( \frac{2.5/75}{2.5/75} \right) = \mathrm{pKa}$$ $$\mathrm{pH} = 4.76$$ $$= 476 \times 10^{-2}$$
Question 84
Chemistry · Chemical Kinetics and Nuclear Chemistry · Numerical
A flask is filled with equal moles of A and B. The half lives of A and B are 100 s and 50 s respectively and are independent of the initial concentration. The time required for the concentration of A to be four times that of B is _________ s. (Given : $\ln 2 = 0.693$)
2.0 g of $\mathrm{H}_2$ gas is adsorbed on 2.5 g of platinum powder at 300 K and 1 bar pressure. The volume of the gas adsorbed per gram of the adsorbent is ________ mL. (Given: R = 0.083 \, $\mathrm{L}$ \, $\mathrm{bar}$ \, $\mathrm{K}^{-1}$ \, $\mathrm{mol}^{-1}$)
Chemistry · The d-and f-Block Elements · Numerical
The spin–only magnetic moment value of the most basic oxide of vanadium among $\mathrm{V_2O_3}$, $\mathrm{V_2O_4}$ and $\mathrm{V_2O_5}$ is ________ B.M. (Nearest Integer)
Answer: 3
Solution
Most basic oxide is $\mathrm{V_2O_3}$. $\mathrm{V^{+3}} \rightarrow [\mathrm{Ar}] \, 3d^2$ $$\mu = \sqrt{2(2+2)} = 2.84 \, \mathrm{BM} \approx 3$$
Question 87
Chemistry · Co-ordination Compounds · Numerical
The spin–only magnetic moment value of an octahedral complex among $CoCl_3.4NH_3$, $NiCl_2.6H_2O$ and $PtCl_4.2HCl$, which upon reaction with excess of $AgNO_3$ gives 2 moles of $AgCl$ is ________ B.M. (Nearest Integer) $\mathrm{CoCl}_3 \cdot 4\mathrm{NH}_3 \rightarrow [\mathrm{Co(NH}_3)_4\mathrm{Cl}_2]\mathrm{Cl}$ $\mathrm{NiCl}_2 \cdot 6\mathrm{H}_2\mathrm{O} \rightarrow [\mathrm{Ni(H}_2\mathrm{O})_6]\mathrm{Cl}_2$ $\mathrm{PtCl}_4 \cdot 2\mathrm{HCl} \rightarrow \mathrm{H}_2[\mathrm{PtCl}_6]$ $[\mathrm{Ni(H}_2\mathrm{O})_6]\mathrm{Cl}_2 \xrightarrow{2\mathrm{AgNO}_3} 2\mathrm{AgCl} \downarrow + [\mathrm{Ni(H}_2\mathrm{O})_6](\mathrm{NO}_3)_2$ $\mu = \sqrt{2(2+2)} \,\mathrm{B.M.}$ $= 2.84 \approx 3$
Chemistry · Some Basic Concepts of Chemistry · Numerical
On complete combustion 0.30 g of an organic compound gave 0.20 g of carbon dioxide and 0.10 g of water. The percentage of carbon in the given organic compound is ______ (Nearest Integer)
Answer: 18
Solution
The reaction is given by: $$\mathrm{C_xH_yO_z} + \left( x + \frac{y}{4} - \frac{z}{2} \right) \mathrm{O_2} \rightarrow x\mathrm{CO_2} + \frac{y}{2} \mathrm{H_2O}$$ Given 0.3 g of $\mathrm{C_xH_yO_z}$ and 0.2 g of $\mathrm{O_2}$ produce 1 g of products. The moles of $\mathrm{CO_2}$ and $\mathrm{H_2O}$ are: $$n_{\mathrm{CO_2}} = \frac{x}{44} = \frac{0.2}{44}$$ $$n_{\mathrm{H_2O}} = \frac{y}{2} = \frac{1}{18}$$ From the equations: $$\frac{2x}{y} = \frac{36}{44} = \frac{9}{11}$$ Solving for $x$: $$x = \frac{9y}{22}$$ The ratio of moles is: $$\frac{n_{\mathrm{C_xH_yO_z}}}{n_{\mathrm{CO_2}}} = \frac{1}{x}$$ Calculating: $$\frac{0.3}{12x + y + 16z} \times \frac{44}{0.2} = \frac{1}{x}$$ Simplifying: $$66x = 12x + y + 16z$$ $$54x = y + 16z$$ Substituting $x$: $$54 \times \frac{9y}{22} = y = 16z$$ Solving for $y$: $$\frac{464y}{22} = 16z$$ Solving for $z$: $$z = \frac{29y}{22}$$ The empirical formula is: $$\mathrm{C_xH_yO_z} = \mathrm{C_xH_yO_z}$$ The molecular formula is: $$\mathrm{C_9H_{22}O_{29}}$$ Calculating the percentage of carbon: $$\% of C = \frac{12 \times 9}{(12 \times 9 + 22 \times 1 + 16 \times 29)} \times 100 = \frac{108}{594} \times 100$$ The percentage of carbon is 18.18%.
Question 89
Chemistry · Amines · Numerical
Compound 'P' on nitration with dil. HNO_3 yields two isomers (A) and (B). These isomers can be separated by steam distillation. Isomers (A) and (B) show the intramolecular and intermolecular hydrogen bonding respectively. Compound (P) on reaction with conc. $HNO_3$ yields a yellow compound 'C', a strong acid. The number of oxygen atoms is present in compound 'C' ________.
Answer: 7
Solution
Question 90
Chemistry · Biomolecules · Numerical
The number of oxygens present in a nucleotide formed from a base, that is present only in RNA is _________.
Answer: 9
Solution
Uracil is the base which only present is RNA. Structure of nucleotides number of 0-9.