JEE Main 2024 — 1 Feb Shift 1 (Previous Year Paper)

JEE Main · 2024 · with answers and explanations

questions
90
Total marks
300
Duration
180 minutes
Negative marking
−1

Subjects: Mathematics · Physics · Chemistry

Question 1

Mathematics · 4 marks · −1

Let S={x∈R:(3+2)x+(3−2)x=10}S=\{x\in\mathbb{R}:(\sqrt3+\sqrt2)^x+(\sqrt3-\sqrt2)^x=10\}. Then the number of elements in SS is:

  1. A.0
  2. B.4
  3. C.1
  4. D.2

Correct answer: D

Explanation: With t=(3+2)xt=(\sqrt3+\sqrt2)^x: t+1t=10t+\frac1t=10 has two positive roots.

Question 2

Mathematics · 4 marks · −1

If 5f(x)+4f(1x)=x2−25f(x)+4f\left(\frac1x\right)=x^2-2, ∀x≠0\forall x\ne0 and y=9x2f(x)y=9x^2f(x), then yy is strictly increasing in:

  1. A.(−15,0)∪(0,15)\left(-\frac1{\sqrt5},0\right)\cup\left(0,\frac1{\sqrt5}\right)
  2. B.(−15,0)∪(15,∞)\left(-\frac1{\sqrt5},0\right)\cup\left(\frac1{\sqrt5},\infty\right)
  3. C.(0,15)∪(15,∞)\left(0,\frac1{\sqrt5}\right)\cup\left(\frac1{\sqrt5},\infty\right)
  4. D.(−∞,15)∪(0,15)\left(-\infty,\frac1{\sqrt5}\right)\cup\left(0,\frac1{\sqrt5}\right)

Correct answer: B

Explanation: 9f(x)=5x2−4x2−29f(x)=5x^2-\frac4{x^2}-2, so y=5x4−2x2−4y=5x^4-2x^2-4; y′=4x(5x2−1)>0y'=4x(5x^2-1)>0.

Question 3

Mathematics · 4 marks · −1

Let 3, a, b, c be in A.P. and 3, a – 1, b + 1, c + 9 be in G.P. Then, the arithmetic mean of a, b and c is:

  1. A.13
  2. B.11
  3. C.−4
  4. D.−1

Correct answer: B

Explanation: (2+d)2=3(4+2d)⇒d=4(2+d)^2=3(4+2d)\Rightarrow d=4 (the other root fails the next ratio); a,b,c=7,11,15a,b,c=7,11,15.

Question 4

Mathematics · 4 marks · −1

The area enclosed by the curves xy+4y=16xy+4y=16 and x+y=6x+y=6 is equal to:

  1. A.30−28log⁡e230-28\log_e2
  2. B.30−32log⁡e230-32\log_e2
  3. C.28−30log⁡e228-30\log_e2
  4. D.32−30log⁡e232-30\log_e2

Correct answer: B

Explanation: Intersections at x=−2,4x=-2,4; ∫−24(6−x−16x+4)dx=30−16ln⁡4=30−32ln⁡2\int_{-2}^{4}\left(6-x-\frac{16}{x+4}\right)dx=30-16\ln4=30-32\ln2.

Question 5

Mathematics · 4 marks · −1

A bag contains 8 balls, whose colours are either white or black. 4 balls are drawn at random without replacement and it was found that 2 balls are white and other 2 balls are black. The probability that the bag contains equal number of white and black balls is:

  1. A.27\frac27
  2. B.15\frac15
  3. C.17\frac17
  4. D.25\frac25

Correct answer: A

Explanation: Equally likely compositions with kk white (k=2,…,6k=2,\ldots,6) have likelihoods ∝kC2 8−kC2=15,30,36,30,15\propto{}^kC_2\,{}^{8-k}C_2=15,30,36,30,15; P(k=4)=36126=27P(k=4)=\frac{36}{126}=\frac27.

Question 6

Mathematics · 4 marks · −1

Let f:R→Rf:\mathbb{R}\to\mathbb{R} and g:R→Rg:\mathbb{R}\to\mathbb{R} be defined as f(x)={log⁡ex,x>0e−x,x≤0f(x)=\begin{cases}\log_ex, & x>0\\ e^{-x}, & x\le0\end{cases} and g(x)={x,x≥0ex,x<0g(x)=\begin{cases}x, & x\ge0\\ e^x, & x<0\end{cases}. Then, g∘f:R→Rg\circ f:\mathbb{R}\to\mathbb{R} is:

  1. A.neither one-one nor onto
  2. B.both one-one and onto
  3. C.onto but not one-one
  4. D.one-one but not onto

Correct answer: A

Explanation: g∘fg\circ f is never negative (not onto) and g(f(x))=1g(f(x))=1 at x=0x=0 and x=ex=e (not one-one).

Question 7

Mathematics · 4 marks · −1

If nn is the number of ways five different employees can sit into four indistinguished offices where any office may have any number of persons including zero, then nn is equal to:

  1. A.43
  2. B.51
  3. C.47
  4. D.53

Correct answer: B

Explanation: S(5,1)+S(5,2)+S(5,3)+S(5,4)=1+15+25+10S(5,1)+S(5,2)+S(5,3)+S(5,4)=1+15+25+10.

Question 8

Mathematics · 4 marks · −1

Let f:R→Rf:\mathbb{R}\to\mathbb{R} be defined as: f(x)={a−bcos⁡2xx2;x<0x2+cx+2;0≤x≤12x+1;x>1f(x)=\begin{cases}\frac{a-b\cos2x}{x^2}; & x<0\\ x^2+cx+2; & 0\le x\le1\\ 2x+1; & x>1\end{cases} If ff is continuous everywhere in R\mathbb{R} and mm is the number of points where ff is NOT differentiable then m+a+b+cm+a+b+c equals:

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

Correct answer: A

Explanation: Continuity: a=ba=b, 2b=22b=2, c=0c=0. Both one-sided derivatives are 0 at x=0x=0 and 2 at x=1x=1, so m=0m=0; m+a+b+c=2m+a+b+c=2.

Question 9

Mathematics · 4 marks · −1

The value of the integral ∫0π/4x dxsin⁡4(2x)+cos⁡4(2x)\int_0^{\pi/4}\frac{x\,dx}{\sin^4(2x)+\cos^4(2x)} equals:

  1. A.2π28\frac{\sqrt2\pi^2}{8}
  2. B.2π216\frac{\sqrt2\pi^2}{16}
  3. C.2π264\frac{\sqrt2\pi^2}{64}
  4. D.2π232\frac{\sqrt2\pi^2}{32}

Correct answer: D

Explanation: King's rule gives I=π8∫0π/4dxsin⁡42x+cos⁡42x=π8⋅π22⋅12I=\frac\pi8\int_0^{\pi/4}\frac{dx}{\sin^42x+\cos^42x}=\frac\pi8\cdot\frac{\pi}{2\sqrt2}\cdot\frac12.

Question 10

Mathematics · 4 marks · −1

If A=[21−12]A=\begin{bmatrix}\sqrt2&1\\-1&\sqrt2\end{bmatrix}, B=[1011]B=\begin{bmatrix}1&0\\1&1\end{bmatrix}, C=ABATC=ABA^T and X=ATC2AX=A^TC^2A, then det X is equal to:

  1. A.27
  2. B.729
  3. C.891
  4. D.243

Correct answer: B

Explanation: ∣A∣=3|A|=3, ∣B∣=1|B|=1: ∣X∣=3⋅92⋅3=729|X|=3\cdot9^2\cdot3=729.

Question 11

Mathematics · 4 marks · −1

If the system of equations 2x+3y−z=52x+3y-z=5 x+αy+3z=−4x+\alpha y+3z=-4 3x−y+βz=73x-y+\beta z=7 has infinitely many solutions, then 13αβ13\alpha\beta is equal to ______.

  1. A.1120
  2. B.1110
  3. C.1220
  4. D.1210

Correct answer: A

Question 12

Mathematics · 4 marks · −1

Let y=y(x)y=y(x) be the solution of the differential equation dydx=2x(x+y)3−x(x+y)−1\frac{dy}{dx}=2x(x+y)^3-x(x+y)-1, y(0)=1y(0)=1. Then, (12+y(12))2\left(\frac1{\sqrt2}+y\left(\frac1{\sqrt2}\right)\right)^2 equal:

  1. A.21+e\frac{2}{1+\sqrt e}
  2. B.44+e\frac{4}{4+\sqrt e}
  3. C.12−e\frac{1}{2-\sqrt e}
  4. D.33−e\frac{3}{3-\sqrt e}

Correct answer: C

Explanation: With u=x+yu=x+y: u′=2xu3−xuu'=2xu^3-xu, a Bernoulli equation; 1u2=2−ex2\frac{1}{u^2}=2-e^{x^2}, so u2=12−eu^2=\frac1{2-\sqrt e} at x2=12x^2=\frac12.

Question 13

Mathematics · 4 marks · −1

Let a⃗=−5i^+j^−3k^\vec a=-5\hat i+\hat j-3\hat k, b⃗=i^+2j^−4k^\vec b=\hat i+2\hat j-4\hat k and c⃗=(((a⃗×b⃗)×i^)×i^)×i^\vec c=(((\vec a\times\vec b)\times\hat i)\times\hat i)\times\hat i. Then c⃗⋅(−i^+j^+k^)\vec c\cdot(-\hat i+\hat j+\hat k) is equal to:

  1. A.−15
  2. B.−12
  3. C.−13
  4. D.−10

Correct answer: B

Explanation: a⃗×b⃗=(2,−23,−11)\vec a\times\vec b=(2,-23,-11); three cross products with i^\hat i give (0,11,−23)(0,11,-23)... c⃗⋅(−1,1,1)=−12\vec c\cdot(-1,1,1)=-12.

Question 14

Mathematics · 4 marks · −1

Let C:x2+y2=4C:x^2+y^2=4 and C′:x2+y2−4λx+9=0C':x^2+y^2-4\lambda x+9=0 be two circles. If the set of all values of λ\lambda so that the circles C and C' intersect at two distinct points, is R−[a,b]\mathbb{R}-[a,b], then the point (8a+12,16b−20)(8a+12,16b-20) lies on the curve:

  1. A.x2−4y2=7x^2-4y^2=7
  2. B.6x2+y2=426x^2+y^2=42
  3. C.5x2−y=−115x^2-y=-11
  4. D.x2+2y2−5x+6y=3x^2+2y^2-5x+6y=3

Correct answer: B

Explanation: ∣2λ∣|2\lambda| must lie strictly between ∣r1−r2∣|r_1-r_2| and r1+r2r_1+r_2: λ∉[−138,138]\lambda\notin[-\frac{13}{8},\frac{13}{8}]; point (−1,6)(-1,6).

Question 15

Mathematics · 4 marks · −1

Let x2a2+y2b2=1\frac{x^2}{a^2}+\frac{y^2}{b^2}=1, a>ba>b be an ellipse, whose eccentricity is 12\frac1{\sqrt2} and the length of the latusrectum is 14\sqrt{14}. Then the square of the eccentricity of x2a2−y2b2=1\frac{x^2}{a^2}-\frac{y^2}{b^2}=1 is:

  1. A.52\frac52
  2. B.3
  3. C.72\frac72
  4. D.32\frac32

Correct answer: D

Explanation: b2=a2/2b^2=a^2/2, so the hyperbola has e2=1+12e^2=1+\frac12.

Question 16

Mathematics · 4 marks · −1

Let S={z∈C:∣z−1∣=1S=\{z\in\mathbb{C}:|z-1|=1 and (2−1)(z+zˉ)−i(z−zˉ)=22}(\sqrt2-1)(z+\bar z)-i(z-\bar z)=2\sqrt2\}. Let z1,z2∈Sz_1,z_2\in S be such that ∣z1∣=max⁡z∈S∣z∣|z_1|=\max_{z\in S}|z| and ∣z2∣=min⁡z∈S∣z∣|z_2|=\min_{z\in S}|z|. Then ∣2z1−z2∣2|\sqrt2z_1-z_2|^2 equals:

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

Correct answer: B

Question 17

Mathematics · 4 marks · −1

If tan⁡A=1x(x2+x+1)\tan A=\frac{1}{\sqrt{x(x^2+x+1)}}, tan⁡B=xx2+x+1\tan B=\frac{\sqrt x}{\sqrt{x^2+x+1}} and tan⁡C=(x−3+x−2+x−1)1/2\tan C=(x^{-3}+x^{-2}+x^{-1})^{1/2}, 0<A,B,C<π20<A,B,C<\frac\pi2, then A+BA+B is equal to:

  1. A.CC
  2. B.π−C\pi-C
  3. C.π2−C\frac\pi2-C
  4. D.2π−C2\pi-C

Correct answer: A

Explanation: tan⁡(A+B)=(1+x)/x(x2+x+1)1−1x2+x+1=tan⁡C\tan(A+B)=\frac{(1+x)/\sqrt{x(x^2+x+1)}}{1-\frac{1}{x^2+x+1}}=\tan C.

Question 18

Mathematics · 4 marks · −1

Let the median and the mean deviation about the median of 7 observation 170, 125, 230, 190, 210, a, b be 170 and 2057\frac{205}{7} respectively. Then the mean deviation about the mean of these 7 observations is:

  1. A.28
  2. B.30
  3. C.31
  4. D.32

Correct answer: B

Question 19

Mathematics · 4 marks · −1

If the shortest distance between the lines x−λ−2=y−21=z−11\frac{x-\lambda}{-2}=\frac{y-2}{1}=\frac{z-1}{1} and x−31=y−1−2=z−21\frac{x-\sqrt3}{1}=\frac{y-1}{-2}=\frac{z-2}{1} is 1, then the sum of all possible values of λ\lambda is:

  1. A.−23-2\sqrt3
  2. B.0
  3. C.333\sqrt3
  4. D.232\sqrt3

Correct answer: D

Explanation: d1×d2=(3,3,3)d_1\times d_2=(3,3,3); ∣3(λ−3)−3+3∣33=1\frac{|3(\lambda-\sqrt3)-3+3|}{3\sqrt3}=1... gives λ=3±3\lambda=\sqrt3\pm\sqrt3; sum 232\sqrt3.

Question 20

Mathematics · 4 marks · −1

For 0<θ<π20<\theta<\frac\pi2, if the eccentricity of the hyperbola x2−y2cosec⁡2θ=5x^2-y^2\operatorname{cosec}^2\theta=5 is 7\sqrt7 times eccentricity of the ellipse x2cosec⁡2θ+y2=5x^2\operatorname{cosec}^2\theta+y^2=5, then the value of θ is:

  1. A.π4\frac\pi4
  2. B.5π12\frac{5\pi}{12}
  3. C.π6\frac\pi6
  4. D.π3\frac\pi3

Correct answer: D

Explanation: 1+sin⁡2θ=7cos⁡2θ⇒cos⁡2θ=141+\sin^2\theta=7\cos^2\theta\Rightarrow\cos^2\theta=\frac14.

Question 21

Mathematics · 4 marks · −1

Let 3, 7, 11, 15, ...., 403 and 2, 5, 8, 11, ...., 404 be two arithmetic progressions. Then the sum, of the common terms in them, is equal to ______.

Correct answer: 6699

Explanation: Common terms 11,23,…,39511,23,\ldots,395 (33 terms): sum 6699.

Question 22

Mathematics · 4 marks · −1

Let the line L:2x+y=αL:\sqrt2x+y=\alpha pass through the point of the intersection P (in the first quadrant) of the circle x2+y2=3x^2+y^2=3 and the parabola x2=2yx^2=2y. Let the line L touch two circles C1C_1 and C2C_2 of equal radius 232\sqrt3. If the centres Q1Q_1 and Q2Q_2 of the circles C1C_1 and C2C_2 lie on the y-axis, then the square of the area of the triangle PQ1Q2PQ_1Q_2 is equal to ______.

Correct answer: 72

Question 23

Mathematics · 4 marks · −1

If ∫−π/2π/282cos⁡x dx(1+esin⁡x)(1+sin⁡4x)=απ+βlog⁡e(3+22)\int_{-\pi/2}^{\pi/2}\frac{8\sqrt2\cos x\,dx}{(1+e^{\sin x})(1+\sin^4x)}=\alpha\pi+\beta\log_e(3+2\sqrt2), where α, β are integers, then α2+β2\alpha^2+\beta^2 equals ______.

Correct answer: 8

Question 24

Mathematics · 4 marks · −1

Let A={1,2,3,…,20}A=\{1,2,3,\ldots,20\}. Let R1R_1 and R2R_2 two relation on A such that, R1={(a,b):bR_1=\{(a,b):b is divisible by a}a\} R2={(a,b):aR_2=\{(a,b):a is an integral multiple of b}b\} Then, number of elements in R1−R2R_1-R_2 is equal to ______.

Correct answer: 46

Question 25

Mathematics · 4 marks · −1

Let the line of the shortest distance between the lines L1:r⃗=(i^+2j^+3k^)+λ(i^−j^+k^)L_1:\vec r=(\hat i+2\hat j+3\hat k)+\lambda(\hat i-\hat j+\hat k) and L2:r⃗=(4i^+5j^+6k^)+μ(i^+j^−k^)L_2:\vec r=(4\hat i+5\hat j+6\hat k)+\mu(\hat i+\hat j-\hat k) intersect L1L_1 and L2L_2 at P and Q respectively. If (α,β,γ)(\alpha,\beta,\gamma) is the mid point of the line segment PQ, then 2(α+β+γ)2(\alpha+\beta+\gamma) is equal to ______.

Correct answer: 21

Question 26

Mathematics · 4 marks · −1

If the coefficient of x30x^{30} in the expansion of (1+1x)6(1+x2)7(1−x3)8\left(1+\frac1x\right)^6(1+x^2)^7(1-x^3)^8; x≠0x\ne0 is α, then |α| equals ______.

Correct answer: 678

Question 27

Mathematics · 4 marks · −1

Let P={z∈C:∣z+2−3i∣≤1}P=\{z\in\mathbb{C}:|z+2-3i|\le1\} and Q={z∈C:z(1+i)+zˉ(1−i)≤−8}Q=\{z\in\mathbb{C}:z(1+i)+\bar z(1-i)\le-8\}. Let in P∩QP\cap Q, ∣z−3+2i∣|z-3+2i| be maximum and minimum at z1z_1 and z2z_2 respectively. If ∣z1∣2+2∣z2∣2=α+β2|z_1|^2+2|z_2|^2=\alpha+\beta\sqrt2, where α, β integers, then α + β equals ______.

Correct answer: 36

Question 28

Mathematics · 4 marks · −1

The number of elements in the set S={(x,y,z):x,y,z∈Z, x+2y+3z=42, x,y,z≥0}S=\{(x,y,z):x,y,z\in\mathbb{Z},\ x+2y+3z=42,\ x,y,z\ge0\} equals ______.

Correct answer: 169

Explanation: ∑z=014(⌊42−3z2⌋+1)=169\sum_{z=0}^{14}\left(\left\lfloor\frac{42-3z}{2}\right\rfloor+1\right)=169.

Question 29

Mathematics · 4 marks · −1

If x=x(t)x=x(t) is the solution of the differential equation (t+1)dx=(2x+(t+1)4)dt(t+1)dx=(2x+(t+1)^4)dt, x(0)=2x(0)=2, then, x(1)x(1) equals ______.

Correct answer: 14

Explanation: ddt(x(t+1)2)=t+1\frac{d}{dt}\left(\frac{x}{(t+1)^2}\right)=t+1; x(t+1)2=(t+1)22+32\frac{x}{(t+1)^2}=\frac{(t+1)^2}{2}+\frac32; x(1)=4(2+1.5)=14x(1)=4(2+1.5)=14.

Question 30

Mathematics · 4 marks · −1

Let {x}\{x\} denote the fractional part of x and f(x)=cos⁡−1(1−{x}2)sin⁡−1(1−{x}){x}−{x}3f(x)=\frac{\cos^{-1}(1-\{x\}^2)\sin^{-1}(1-\{x\})}{\{x\}-\{x\}^3}, x≠0x\ne0. If L and R respectively denotes the left hand limit and the right hand limit of f(x)f(x) at x=0x=0, then 32π2(L2+R2)\frac{32}{\pi^2}(L^2+R^2) is equal to ______.

Correct answer: 18

Question 31

Physics · 4 marks · −1

A galvanometer has a resistance of 50Ω and it allows maximum current of 5 mA. It can be converted into voltmeter to measure upto 100 V by connecting in series a resistor of resistance:

  1. A.5975Ω
  2. B.20050Ω
  3. C.19500Ω
  4. D.19950Ω

Correct answer: D

Explanation: R=1000.005−50R=\frac{100}{0.005}-50.

Question 32

Physics · 4 marks · −1

In the given circuit if the power rating of Zener diode is 10 mW, the value of series resistance RsR_s to regulate the input unregulated supply is:

Figure for question 32
  1. A.37\frac37 kΩ
  2. B.10 Ω
  3. C.1 kΩ
  4. D.10 kΩ

Correct answer: A

Explanation: Max Zener current =10 mW5 V=2=\frac{10\text{ mW}}{5\text{ V}}=2 mA; load 5 mA; Rs=3 V7 mA=37R_s=\frac{3\text{ V}}{7\text{ mA}}=\frac37 kΩ.

Question 33

Physics · 4 marks · −1

In series LCR circuit, the capacitance is changed from C to 4C. To keep the resonance frequency unchanged, the new inductance should be:

  1. A.reduced by 14L\frac14L
  2. B.reduced by 34L\frac34L
  3. C.increased to 4 L
  4. D.increased by 2 L

Correct answer: B

Question 34

Physics · 4 marks · −1

The dimensional formula of angular impulse is:

  1. A.[ML−2T−1][ML^{-2}T^{-1}]
  2. B.[ML2T−2][ML^2T^{-2}]
  3. C.[ML2T−1][ML^2T^{-1}]
  4. D.[MLT−1][MLT^{-1}]

Correct answer: C

Question 35

Physics · 4 marks · −1

If R is the radius of the earth and the acceleration due to gravity on the surface of earth is g=π2g=\pi^2 m/s², then the length of the second's pendulums at a height h = 2R from the surface of earth will be:

  1. A.49\frac49 m
  2. B.29\frac29 m
  3. C.19\frac19 m
  4. D.89\frac89 m

Correct answer: C

Explanation: g′=g9g'=\frac g9; L=g′T24π2=19L=\frac{g'T^2}{4\pi^2}=\frac19 m.

Question 36

Physics · 4 marks · −1

The de-Broglie wavelengths of a proton and an α particle are λ and 2λ respectively. The ratio of the velocities of proton and α particle will be:

  1. A.8 : 1
  2. B.4 : 1
  3. C.1 : 2
  4. D.1 : 8

Correct answer: A

Explanation: v=hmλv=\frac{h}{m\lambda}: vpvα=4m⋅2λmλ=8\frac{v_p}{v_\alpha}=\frac{4m\cdot2\lambda}{m\lambda}=8.

Question 37

Physics · 4 marks · −1

Consider a block and trolley system as shown in figure. If the coefficient of kinetic friction between the trolley and the surface is 0.04, the acceleration of the system in m s−2^{-2} is: (Consider that the string is massless and unstretchable and the pulley is also massless and frictionless):

Figure for question 37
  1. A.3
  2. B.1.2
  3. C.4
  4. D.2

Correct answer: D

Explanation: a=60−0.04×20026=2a=\frac{60-0.04\times200}{26}=2 m/s².

Question 38

Physics · 4 marks · −1

A ball of mass 0.5 kg is attached to a string of length 50 cm. The ball is rotated on a horizontal circular path about its vertical axis. The maximum tension that the string can bear is 400 N. The maximum possible value of angular velocity of the ball in rad/s is:

  1. A.1000
  2. B.1600
  3. C.40
  4. D.20

Correct answer: C

Explanation: 400=0.5 ω2(0.5)400=0.5\,\omega^2(0.5).

Question 39

Physics · 4 marks · −1

Two moles a monoatomic gas is mixed with six moles of diatomic gas. The molar specific heat of the mixture at constant volume is:

  1. A.74R\frac74R
  2. B.94R\frac94R
  3. C.32R\frac32R
  4. D.52R\frac52R

Correct answer: B

Explanation: 2(1.5)+6(2.5)8R\frac{2(1.5)+6(2.5)}{8}R.

Question 40

Physics · 4 marks · −1

A parallel plate capacitor has a capacitance C = 200 pF. It is connected to 230 V ac supply with an angular frequency 300 rad/s. The rms value of conduction current in the circuit and displacement current in the capacitor respectively are:

  1. A.1.38 μA and 1.38 μA
  2. B.13.8 μA and 138 μA
  3. C.14.3 μA and 143 μA
  4. D.13.8 μA and 13.8 μA

Correct answer: D

Explanation: I=VωC=230×300×2×10−10=13.8I=V\omega C=230\times300\times2\times10^{-10}=13.8 μA, equal to the displacement current.

Question 41

Physics · 4 marks · −1

The minimum energy required by a hydrogen atom in ground state to emit radiation in Balmer series is nearly:

  1. A.13.6 eV
  2. B.1.9 eV
  3. C.12.1 eV
  4. D.1.5 eV

Correct answer: C

Explanation: Excite to n=3n=3: 12.1 eV.

Question 42

Physics · 4 marks · −1

The pressure and volume of an ideal gas are related as PV3/2=KPV^{3/2}=K (constant). The work done when the gas is taken from state A(P1,V1,T1)A(P_1,V_1,T_1) to state B(P2,V2,T2)B(P_2,V_2,T_2) is:

  1. A.2(P2V2−P1V1)2(P_2\sqrt{V_2}-P_1\sqrt{V_1})
  2. B.2(P1V1−P2V2)2(P_1V_1-P_2V_2)
  3. C.2(P2V2−P1V1)2(P_2V_2-P_1V_1)
  4. D.2(P1V1−P2V2)2(\sqrt{P_1}V_1-\sqrt{P_2}V_2)

Correct answer: B

Explanation: W=P1V1−P2V2n−1W=\frac{P_1V_1-P_2V_2}{n-1} with n=32n=\frac32.

Question 43

Physics · 4 marks · −1

The radius (r), length (l) and resistance (R) of a metal wire was measured in the laboratory as r=(0.35±0.05)r=(0.35\pm0.05) cm, R=(100±10)R=(100\pm10) ohm, l=(15±0.2)l=(15\pm0.2) cm. The percentage error in resistivity of the material of the wire is:

  1. A.35.6%
  2. B.37.3%
  3. C.39.9%
  4. D.25.6%

Correct answer: C

Explanation: 2(14.29)+10+1.33=39.9%2(14.29)+10+1.33=39.9\%.

Question 44

Physics · 4 marks · −1

A particle moving in a circle of radius R with uniform speed takes time T to complete one revolution. If this particle is projected with the same speed at an angle θ to the horizontal, the maximum height attained by it is equal to 4R. The angle of projection θ is then given by:

  1. A.sin⁡−1[π2R2gT2]1/2\sin^{-1}\left[\frac{\pi^2R}{2gT^2}\right]^{1/2}
  2. B.sin⁡−1[2gT2π2R]1/2\sin^{-1}\left[\frac{2gT^2}{\pi^2R}\right]^{1/2}
  3. C.cos⁡−1[2gT2π2R]1/2\cos^{-1}\left[\frac{2gT^2}{\pi^2R}\right]^{1/2}
  4. D.cos⁡−1[πR2gT2]1/2\cos^{-1}\left[\frac{\pi R}{2gT^2}\right]^{1/2}

Correct answer: B

Explanation: v2sin⁡2θ2g=4R\frac{v^2\sin^2\theta}{2g}=4R with v=2πRTv=\frac{2\pi R}{T}.

Question 45

Physics · 4 marks · −1

A monochromatic light of wavelength 6000 Å is incident on the single slit of width 0.01 mm. If the diffraction pattern is formed at the focus of the convex lens of focal length 20 cm, the linear width of the central maximum is:

  1. A.120 mm
  2. B.12 mm
  3. C.60 mm
  4. D.24 mm

Correct answer: D

Explanation: 2λfa=24\frac{2\lambda f}{a}=24 mm.

Question 46

Physics · 4 marks · −1

10 divisions on the main scale of a vernier calliper coincide with 11 divisions on the Vernier scale. If each division on the main scale is of 5 units, the least count of the instrument is:

  1. A.511\frac5{11}
  2. B.1011\frac{10}{11}
  3. C.12\frac12
  4. D.5011\frac{50}{11}

Correct answer: A

Explanation: LC =111=\frac{1}{11} MSD.

Question 47

Physics · 4 marks · −1

With rise in temperature, the Young's modulus of elasticity:

  1. A.increases
  2. B.changes erratically
  3. C.decreases
  4. D.remains unchanged

Correct answer: C

Question 48

Physics · 4 marks · −1

A simple pendulum of length 1 m has a wooden bob of mass 1 kg. It is struck by a bullet of mass 10−210^{-2} kg moving with a speed of 2×1022\times10^2 m/s. The bullet gets embedded into the bob. The height to which the bob rises before swinging back is: [Use : g = 10 m/s²]

  1. A.0.30 m
  2. B.0.40 m
  3. C.0.20 m
  4. D.0.35 m

Correct answer: C

Explanation: v=21.01≈1.98v=\frac{2}{1.01}\approx1.98 m/s; h=v22g≈0.20h=\frac{v^2}{2g}\approx0.20 m.

Question 49

Physics · 4 marks · −1

The reading in the ideal voltmeter (V) shown in the given circuit diagram is:

Figure for question 49
  1. A.0 V
  2. B.3 V
  3. C.5 V
  4. D.10 V

Correct answer: A

Explanation: Current =401.6=25=\frac{40}{1.6}=25 A; terminal voltage of each cell =5−25(0.2)=0=5-25(0.2)=0.

Question 50

Physics · 4 marks · −1

Two identical capacitors have same capacitance C. One of them is charged to the potential V and other to the potential 2V. The negative ends of both are connected together. When the positive ends are also joined together, the decrease in energy of the combined system is:

  1. A.34CV2\frac34CV^2
  2. B.14CV2\frac14CV^2
  3. C.12CV2\frac12CV^2
  4. D.2CV22CV^2

Correct answer: B

Explanation: ΔU=C22(2C)(2V−V)2\Delta U=\frac{C^2}{2(2C)}(2V-V)^2.

Question 51

Physics · 4 marks · −1

A particle is moving in one dimension (along x axis) under the action of a variable force. It's initial position was 16 m right of origin. The variation of its position (x) with time (t) is given as x=−3t3+18t2+16tx=-3t^3+18t^2+16t, where x is in m and t is in s. The velocity of the particle when its acceleration becomes zero is ______ m/s.

Correct answer: 52

Explanation: a=−18t+36=0a=-18t+36=0 at t=2t=2; v=−36+72+16=52v=-36+72+16=52.

Question 52

Physics · 4 marks · −1

A tuning fork resonates with a sonometer wire of length 1 m stretched with tension of 6 N. When the tension in the wire is changed to 54 N, the same tuning fork produces 12 beats per second with it. The frequency of the tuning fork is ______ Hz.

Correct answer: 6

Explanation: Frequency triples: 3f−f=123f-f=12.

Question 53

Physics · 4 marks · −1

A plane is in level flight at constant speed and each of its two wings has an area of 40 m². If the speed of the air is 180 km/h over the lower wing surface and 252 km/h over the upper wing surface, the mass of the plane is ______ kg. [Take air density to be 1 kg m−3^{-3} and g = 10 m s−2^{-2}]

Correct answer: 9600

Explanation: ΔP=12(702−502)=1200\Delta P=\frac12(70^2-50^2)=1200 Pa; lift =1200×80=1200\times80 N; mass 9600 kg.

Question 54

Physics · 4 marks · −1

A regular polygon of 6 sides is formed by bending a wire of length 4π meter. If an electric current of 4π34\pi\sqrt3 A is flowing through the sides of the polygon, the magnetic field at the centre of the polygon would be x×10−7x\times10^{-7} T. The value of x is ______.

Correct answer: 72

Explanation: Side 2π3\frac{2\pi}{3}, distance to side π3\frac{\pi}{\sqrt3}; B=6⋅10−7⋅Id(2sin⁡30∘)=72×10−7B=6\cdot10^{-7}\cdot\frac{I}{d}(2\sin30^\circ)=72\times10^{-7} T.

Question 55

Physics · 4 marks · −1

The current in a conductor is expressed as I=3t2+4t3I=3t^2+4t^3, where I is in Ampere and t is in second. The amount of electric charge that flows through a section of the conductor during t = 1s to t = 2s is ______ C.

Correct answer: 22

Explanation: [t3+t4]12=24−2=22[t^3+t^4]_1^2=24-2=22.

Question 56

Physics · 4 marks · −1

The distance between object and its 3 times magnified virtual image as produced by a convex lens is 20 cm. The focal length of the lens used is ______ cm.

Correct answer: 15

Explanation: u=−10u=-10, v=−30v=-30; f=15f=15 cm.

Question 57

Physics · 4 marks · −1

The identical spheres each of mass 2 M are placed at the corners of a right angled triangle with mutually perpendicular sides equal to 4 m each. Taking point of intersection of these two sides as origin, the magnitude of position vector of the centre of mass of the system is 42x\frac{4\sqrt2}{x}, where the value of x is ______.

Correct answer: 3

Explanation: CM =(43,43)=(\frac43,\frac43).

Question 58

Physics · 4 marks · −1

A rectangular loop of sides 12 cm and 5 cm, with its sides parallel to the x-axis and y-axis respectively, moves with a velocity of 5 cm/s in the positive x axis direction, in a space containing a variable magnetic field in the positive z direction. The field has a gradient of 10−310^{-3} T/cm along the negative x direction and it is decreasing with time at the rate of 10−310^{-3} T/s. If the resistance of the loop is 6 mΩ, the power dissipated by the loop as heat is ______ ×10−9\times10^{-9} W.

Correct answer: 216

Explanation: dΦdt=A(∂B∂xv+∂B∂t)\frac{d\Phi}{dt}=A\left(\frac{\partial B}{\partial x}v+\frac{\partial B}{\partial t}\right): both terms decrease the flux: 60×10−4(0.1×0.05+10−3)=3.6×10−560\times10^{-4}(0.1\times0.05+10^{-3})=3.6\times10^{-5} V... P=ε2R=216×10−9P=\frac{\varepsilon^2}{R}=216\times10^{-9} W.

Question 59

Physics · 4 marks · −1

The radius of a nucleus of mass number 64 is 4.8 fermi. Then the mass number of another nucleus having radius of 4 fermi is 1000x\frac{1000}{x}, where x is ______.

Correct answer: 27

Explanation: A=64(44.8)3=100027A=64\left(\frac{4}{4.8}\right)^3=\frac{1000}{27}.

Question 60

Physics · 4 marks · −1

Two identical charged spheres are suspended by strings of equal lengths. The string make an angle θ with each other. When suspended in water the angle remains the same. If density of the material of the sphere is 1.5 g/cc, the dielectric constant of water will be ______. [Take density of water = 1 g/cc]

Correct answer: 3

Explanation: K=ρρ−σ=3K=\frac{\rho}{\rho-\sigma}=3.

Question 61

Chemistry · 4 marks · −1

Which of the following compound will most easily be attacked by an electrophile?

  1. A.Phenol
  2. B.Chlorobenzene
  3. C.Toluene
  4. D.Benzene

Correct answer: A

Question 62

Chemistry · 4 marks · −1

In case of isoelectronic species the size of F−\text{F}^-, Ne and Na+\text{Na}^+ is affected by:

  1. A.None of the factors because their size is the same
  2. B.Electron-electron interaction in the outer orbitals
  3. C.Principal quantum number (n)
  4. D.Nuclear charge (z)

Correct answer: D

Question 63

Chemistry · 4 marks · −1

Which of the following reactions are disproportionation reactions? (A) Cu+→Cu2++Cu\text{Cu}^+\to\text{Cu}^{2+}+\text{Cu} (B) 3MnO42−+4H+→2MnO4−+MnO2+2H2O3\text{MnO}_4^{2-}+4\text{H}^+\to2\text{MnO}_4^-+\text{MnO}_2+2\text{H}_2\text{O} (C) 2KMnO4→K2MnO4+MnO2+O22\text{KMnO}_4\to\text{K}_2\text{MnO}_4+\text{MnO}_2+\text{O}_2 (D) 2MnO4−+3Mn2++2H2O→5MnO2+4H+2\text{MnO}_4^-+3\text{Mn}^{2+}+2\text{H}_2\text{O}\to5\text{MnO}_2+4\text{H}^+ Choose the correct answer from the options given below:

  1. A.(B), (C), (D)
  2. B.(A), (B), (C)
  3. C.(A), (B)
  4. D.(A), (D)

Correct answer: C

Explanation: (D) is comproportionation; (C) involves different elements being oxidised/reduced.

Question 64

Chemistry · 4 marks · −1

We have three aqueous solutions of NaCl labelled as 'A', 'B' and 'C' with concentration 0.1 M, 0.01 M, 0.001 M, respectively. The value of van't Hoff factor (i) for these solutions will be in the order:

  1. A.iA<iC<iBi_A<i_C<i_B
  2. B.iA<iB<iCi_A<i_B<i_C
  3. C.iA>iB>iCi_A>i_B>i_C
  4. D.iA=iB=iCi_A=i_B=i_C

Correct answer: B

Explanation: Dissociation is more complete at higher dilution.

Question 65

Chemistry · 4 marks · −1

Match List-I with List-II. List-I (Reactions): (A) CH3(CH2)5COOC2H5→CH3(CH2)5CHO\text{CH}_3(\text{CH}_2)_5\text{COOC}_2\text{H}_5\to\text{CH}_3(\text{CH}_2)_5\text{CHO}; (B) C6H5COC6H5→C6H5CH2C6H5\text{C}_6\text{H}_5\text{COC}_6\text{H}_5\to\text{C}_6\text{H}_5\text{CH}_2\text{C}_6\text{H}_5; (C) C6H5CHO→C6H5CH(OH)CH3\text{C}_6\text{H}_5\text{CHO}\to\text{C}_6\text{H}_5\text{CH(OH)CH}_3; (D) CH3COCH2COOC2H5→CH3CH(OH)CH2COOC2H5\text{CH}_3\text{COCH}_2\text{COOC}_2\text{H}_5\to\text{CH}_3\text{CH(OH)CH}_2\text{COOC}_2\text{H}_5 List-II (Reagents): (I) CH3MgBr\text{CH}_3\text{MgBr}, H2O\text{H}_2\text{O}; (II) Zn(Hg) and conc. HCl; (III) NaBH4\text{NaBH}_4, H+\text{H}^+; (IV) DIBAL-H, H2O\text{H}_2\text{O} Choose the correct answer from the options given below:

  1. A.(A)-(IV), (B)-(II), (C)-(I), (D)-(III)
  2. B.(A)-(IV), (B)-(II), (C)-(III), (D)-(I)
  3. C.(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
  4. D.(A)-(III), (B)-(IV), (C)-(II), (D)-(I)

Correct answer: A

Question 66

Chemistry · 4 marks · −1

Ionic reactions with organic compounds proceed through: (A) homolytic bond cleavage (B) heterolytic bond cleavage (C) free radical formation (D) primary free radical (E) secondary free radical Choose the correct answer from the options given below:

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

Correct answer: D

Question 67

Chemistry · 4 marks · −1

In acidic medium, K2Cr2O7\text{K}_2\text{Cr}_2\text{O}_7 shows oxidising action as represented in the half reaction: Cr2O72−+XH++Ye−→2A+ZH2O\text{Cr}_2\text{O}_7^{2-}+X\text{H}^++Y\text{e}^-\to2A+Z\text{H}_2\text{O}. X, Y, Z and A respectively are:

  1. A.8, 6, 4 and Cr2O3\text{Cr}_2\text{O}_3
  2. B.8, 4, 6 and Cr2O3\text{Cr}_2\text{O}_3
  3. C.14, 6, 7 and Cr3+\text{Cr}^{3+}
  4. D.14, 7, 6 and Cr3+\text{Cr}^{3+}

Correct answer: C

Question 68

Chemistry · 4 marks · −1

Choose the correct option for free expansion of an ideal gas under adiabatic condition from the following:

  1. A.q = 0, ΔT < 0, w ≠ 0
  2. B.q = 0, ΔT = 0, w = 0
  3. C.q = 0, ΔT ≠ 0, w = 0
  4. D.q ≠ 0, ΔT = 0, w = 0

Correct answer: B

Question 69

Chemistry · 4 marks · −1

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Haloalkanes react with KCN to form alkyl cyanides as a main product while with AgCN form isocyanide as the main product. Reason (R) : KCN and AgCN both are highly ionic compounds. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Both (A) and (R) are correct and (R) is the correct explanation of (A)
  2. B.(A) is not correct (R) is correct
  3. C.Both (A) and (R) are correct but (R) is not the correct explanation of (A)
  4. D.(A) is correct (R) is not correct

Correct answer: D

Explanation: AgCN is largely covalent.

Question 70

Chemistry · 4 marks · −1

Given below are two statements: Statement (I) : A solution of [Ni(H2O)6]2+[\text{Ni(H}_2\text{O)}_6]^{2+} is green in colour. Statement (II) : A solution of [Ni(CN)4]2−[\text{Ni(CN)}_4]^{2-} is colourless. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Both Statement I and Statement II are correct
  2. B.Both Statement I and Statement II are incorrect
  3. C.Statement I is correct but Statement II is incorrect
  4. D.Statement I is incorrect but Statement II is correct

Correct answer: A

Question 71

Chemistry · 4 marks · −1

Given below are two statements: Statement (I) : Potassium hydrogen phthalate is primary standard for standardisation of sodium hydroxide solution. Statement (II) : In this titration phenolphthalein can be used as indicator. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Both Statement I and Statement II are incorrect
  2. B.Statement I is incorrect but Statement II is correct
  3. C.Statement I is correct but Statement II is incorrect
  4. D.Both Statement I and Statement II are correct

Correct answer: D

Question 72

Chemistry · 4 marks · −1

Given below are two statements: Statement (I) : The NH2\text{NH}_2 group in aniline is ortho and para directing and powerful activating group. Statement (II) : Aniline does not undergo Friedel-Craft's reaction (alkylation and acylation). In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Both Statement I and Statement II are correct
  2. B.Statement I is incorrect but Statement II is correct
  3. C.Statement I is correct but Statement II is incorrect
  4. D.Both Statement I and Statement II are incorrect

Correct answer: A

Question 73

Chemistry · 4 marks · −1

Which of the following complex is homoleptic?

  1. A.[Fe(NH3)4Cl2]+[\text{Fe(NH}_3)_4\text{Cl}_2]^+
  2. B.[Ni(CN)4]2−[\text{Ni(CN)}_4]^{2-}
  3. C.[Co(NH3)4Cl2]+[\text{Co(NH}_3)_4\text{Cl}_2]^+
  4. D.[Ni(NH3)2Cl2][\text{Ni(NH}_3)_2\text{Cl}_2]

Correct answer: B

Question 74

Chemistry · 4 marks · −1

Given below are two statements: Statement (I) : Aminobenzene and aniline are same organic compounds. Statement (II) : Aminobenzene and aniline are different organic compounds. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Statement I is correct but Statement II is incorrect
  2. B.Both Statement I and Statement II are incorrect
  3. C.Statement I is incorrect but Statement II is correct
  4. D.Both Statement I and Statement II are correct

Correct answer: A

Question 75

Chemistry · 4 marks · −1

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : PH3\text{PH}_3 has lower boiling point the NH3\text{NH}_3. Reason (R) : In liquid state NH3\text{NH}_3 molecules are associated through vander Waal's forces, but PH3\text{PH}_3 molecules are associated through hydrogen bonding. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Both (A) and (R) are correct and (R) is the correct explanation of (A)
  2. B.Both (A) and (R) are correct but (R) is not the correct explanation of (A)
  3. C.(A) is correct (R) is not correct
  4. D.(A) is not correct (R) is correct

Correct answer: C

Question 76

Chemistry · 4 marks · −1

In Kjeldahl's method for estimation of nitrogen, CuSO4\text{CuSO}_4 acts as:

  1. A.reducing agent
  2. B.hydrolysis agent
  3. C.catalytic agent
  4. D.oxidizing agent

Correct answer: C

Question 77

Chemistry · 4 marks · −1

If one strand of a DNA has the sequence ATGCTTCA, sequence of the bases in complementary stand is:

  1. A.GTACTTAC
  2. B.TACGAAGT
  3. C.CATTAGCT
  4. D.ATGCGACT

Correct answer: B

Question 78

Chemistry · 4 marks · −1

Identify A and B in the following sequence of reaction: Toluene →Cl2/hν\xrightarrow{\text{Cl}_2/h\nu} A →H2O, 373 K\xrightarrow{\text{H}_2\text{O},\ 373\text{ K}} B

  1. A.A = benzoyl chloride, B = benzaldehyde
  2. B.A = benzal chloride (C6H5CHCl2\text{C}_6\text{H}_5\text{CHCl}_2), B = benzoic acid
  3. C.A = benzyl chloride, B = benzaldehyde
  4. D.A = benzal chloride (C6H5CHCl2\text{C}_6\text{H}_5\text{CHCl}_2), B = benzaldehyde

Correct answer: D

Question 79

Chemistry · 4 marks · −1

Arrange the bonds in order of increasing ionic character in the molecules LiF, K2O\text{K}_2\text{O}, N2\text{N}_2, SO2\text{SO}_2 and ClF3\text{ClF}_3

  1. A.N2<SO2<ClF3<K2O<LiF\text{N}_2<\text{SO}_2<\text{ClF}_3<\text{K}_2\text{O}<\text{LiF}
  2. B.LiF<K2O<ClF3<SO2<N2\text{LiF}<\text{K}_2\text{O}<\text{ClF}_3<\text{SO}_2<\text{N}_2
  3. C.N2<ClF3<SO2<K2O<LiF\text{N}_2<\text{ClF}_3<\text{SO}_2<\text{K}_2\text{O}<\text{LiF}
  4. D.ClF3<N2<SO2<K2O<LiF\text{ClF}_3<\text{N}_2<\text{SO}_2<\text{K}_2\text{O}<\text{LiF}

Correct answer: A

Question 80

Chemistry · 4 marks · −1

According to the wave-particle duality of matter by de-Broglie, which of the following graph plot presents most appropriate relationship between wavelength of electron (λ) and momentum of electron (p)?

Figure for question 80
  1. A.λ vs p: rectangular hyperbola
  2. B.λ vs 1/p: decreasing hyperbola
  3. C.p vs λ: straight line through origin
  4. D.λ vs p: straight line through origin

Correct answer: A

Explanation: λ=h/p\lambda=h/p.

Question 81

Chemistry · 4 marks · −1

The number of molecules/ion/s having trigonal bipyramidal shape is ______. PF5\text{PF}_5, BrF5\text{BrF}_5, PCl5\text{PCl}_5, [PtCl4]2−[\text{PtCl}_4]^{2-}, BF3\text{BF}_3, Fe(CO)5\text{Fe(CO)}_5

Correct answer: 3

Question 82

Chemistry · 4 marks · −1

Number of optical isomers for 2-chlorobutane ______.

Correct answer: 2

Question 83

Chemistry · 4 marks · −1

Consider the following reaction: 3PbCl2+2(NH4)3PO4→Pb3(PO4)2+6NH4Cl3\text{PbCl}_2+2(\text{NH}_4)_3\text{PO}_4\to\text{Pb}_3(\text{PO}_4)_2+6\text{NH}_4\text{Cl}. If 72 mmol of PbCl2\text{PbCl}_2 is mixed with 50 mmol of (NH4)3PO4(\text{NH}_4)_3\text{PO}_4, then the amount of Pb3(PO4)2\text{Pb}_3(\text{PO}_4)_2 formed is ______ mmol. (Nearest integer)

Correct answer: 24

Explanation: PbCl2\text{PbCl}_2 limiting: 24 mmol.

Question 84

Chemistry · 4 marks · −1

Among the following oxides of p-block elements, number of oxides having amphoteric nature is ______. Cl2O7\text{Cl}_2\text{O}_7, CO, PbO2\text{PbO}_2, N2O\text{N}_2\text{O}, NO, Al2O3\text{Al}_2\text{O}_3, SiO2\text{SiO}_2, N2O5\text{N}_2\text{O}_5, SnO2\text{SnO}_2

Correct answer: 3

Explanation: PbO2_2, Al2_2O3_3, SnO2_2.

Question 85

Chemistry · 4 marks · −1

The potential for the given half cell at 298 K is (–) ______ ×10−2\times10^{-2} V. 2H+(aq)+2e−→H2(g)2\text{H}^+(aq)+2e^-\to\text{H}_2(g); [H+]=1[\text{H}^+]=1 M, PH2=2P_{\text{H}_2}=2 atm [Given : 2.303 RT/F = 0.06 V, log 2 = 0.3]

Correct answer: 1

Explanation: E=−0.062log⁡2=−0.009E=-\frac{0.06}{2}\log2=-0.009 V ≈ −1×10−2-1\times10^{-2} V.

Question 86

Chemistry · 4 marks · −1

The lowest oxidation number of an atom in a compound A2B\text{A}_2\text{B} is −2. The number of electrons in its valence shell is ______.

Correct answer: 6

Question 87

Chemistry · 4 marks · −1

The ratio of 14C12C\frac{^{14}\text{C}}{^{12}\text{C}} in a piece of wood is 18\frac18 part that of atmosphere. If half life of 14^{14}C is 5730 years, the age of wood sample is ______ years.

Correct answer: 17190

Explanation: Three half-lives.

Question 88

Chemistry · 4 marks · −1

Total number of deactivating groups in aromatic electrophilic substitution reaction among the following is ______. −COOCH3-\text{COOCH}_3 (ester), −NHCOCH3-\text{NHCOCH}_3, −NHCH3-\text{NHCH}_3, −C≡N-\text{C}\equiv\text{N}, −OCH3-\text{OCH}_3

Figure for question 88

Correct answer: 2

Explanation: −COOCH3-\text{COOCH}_3 and −CN-\text{CN}.

Question 89

Chemistry · 4 marks · −1

The number of white coloured salts, among the following is ______. (a) SrSO4\text{SrSO}_4 (b) Mg(NH4)PO4\text{Mg(NH}_4)\text{PO}_4 (c) BaCrO4\text{BaCrO}_4 (d) Mn(OH)2\text{Mn(OH)}_2 (e) PbSO4\text{PbSO}_4 (f) PbCrO4\text{PbCrO}_4 (g) AgBr (h) PbI2\text{PbI}_2 (i) CaC2O4\text{CaC}_2\text{O}_4 (j) [Fe(OH)2(CH3COO)][\text{Fe(OH)}_2(\text{CH}_3\text{COO})]

Correct answer: 5

Explanation: SrSO4_4, MgNH4_4PO4_4, Mn(OH)2_2, PbSO4_4, CaC2_2O4_4.

Question 90

Chemistry · 4 marks · −1

KaK_a for CH3COOH\text{CH}_3\text{COOH} is 1.8×10−51.8\times10^{-5} and KbK_b for NH4OH\text{NH}_4\text{OH} is 1.8×10−51.8\times10^{-5}. The pH of ammonium acetate solution will be ______.

Correct answer: 7

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