JEE Main 2024 — 1 Feb Shift 2 (Previous Year Paper)

JEE Main · 2024 · with answers and explanations

questions
88
Total marks
292
Duration
180 minutes
Negative marking
−1

Subjects: Mathematics · Physics · Chemistry

Question 1

Mathematics · 4 marks · −1

Let α and β be the roots of the equation px2+qx−r=0px^2+qx-r=0, where p≠0p\ne0. If p, q and r be the consecutive terms of a non constant G.P. and 1α+1β=34\frac1\alpha+\frac1\beta=\frac34, then the value of (α−β)2(\alpha-\beta)^2 is:

  1. A.809\frac{80}{9}
  2. B.203\frac{20}{3}
  3. C.9
  4. D.8

Correct answer: A

Explanation: qr=34\frac q r=\frac34 with q2=prq^2=pr gives r=43qr=\frac43q, p=34qp=\frac34q; (α−β)2=q2+4prp2=809(\alpha-\beta)^2=\frac{q^2+4pr}{p^2}=\frac{80}{9}.

Question 2

Mathematics · 4 marks · −1

If the mirror image of the point P(3, 4, 9) in the line x−13=y+12=z−21\frac{x-1}{3}=\frac{y+1}{2}=\frac{z-2}{1} is (α,β,γ)(\alpha,\beta,\gamma), then 14(α+β+γ)14(\alpha+\beta+\gamma) is:

  1. A.138
  2. B.132
  3. C.102
  4. D.108

Correct answer: D

Explanation: Foot at t=2314t=\frac{23}{14}; image sum =2(2+6t)−16=10814=2(2+6t)-16=\frac{108}{14}.

Question 3

Mathematics · 4 marks · −1

Let Ajay will not appear in JEE exam with probability p=27p=\frac27, while both Ajay and Vijay will appear in the exam with probability q=15q=\frac15. Then the probability, that Ajay will appear in the exam and Vijay will not appear is:

  1. A.1835\frac{18}{35}
  2. B.935\frac9{35}
  3. C.335\frac3{35}
  4. D.2435\frac{24}{35}

Correct answer: A

Explanation: 57−15=1835\frac57-\frac15=\frac{18}{35}.

Question 4

Mathematics · 4 marks · −1

The number of solutions of the equation 4sin⁡2x−4cos⁡3x+9−4cos⁡x=04\sin^2x-4\cos^3x+9-4\cos x=0; x∈[−2π,2π]x\in[-2\pi,2\pi] is:

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

Correct answer: A

Explanation: With c=cos⁡xc=\cos x: 4c3+4c2+4c−13=04c^3+4c^2+4c-13=0 has its only real root above 1.

Question 5

Mathematics · 4 marks · −1

Let P and Q be the points on the line x+38=y−42=z+12\frac{x+3}{8}=\frac{y-4}{2}=\frac{z+1}{2} which are at a distance of 6 units from the point R (1, 2, 3). If the centroid of the tringle PQR is (α,β,γ)(\alpha,\beta,\gamma), then α2+β2+γ2\alpha^2+\beta^2+\gamma^2 is:

  1. A.24
  2. B.36
  3. C.26
  4. D.18

Correct answer: C

Explanation: The foot of the perpendicular from R is the midpoint M of PQ: M=(1,5,0)M=(1,5,0); centroid 2M+R3=(1,4,1)\frac{2M+R}{3}=(1,4,1).

Question 6

Mathematics · 4 marks · −1

Consider 10 observations x1,x2,…,x10x_1,x_2,\ldots,x_{10} such that ∑i=110(xi−α)=2\sum_{i=1}^{10}(x_i-\alpha)=2 and ∑i=110(xi−β)2=40\sum_{i=1}^{10}(x_i-\beta)^2=40, where α, β are positive integers. Let the mean and the variance of the observations be 65\frac65 and 8425\frac{84}{25} respectively. Then βα\frac\beta\alpha is equal to:

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

Correct answer: B

Explanation: α=1\alpha=1; 4010=σ2+(xˉ−β)2⇒(1.2−β)2=0.64\frac{40}{10}=\sigma^2+(\bar x-\beta)^2\Rightarrow(1.2-\beta)^2=0.64, β=2\beta=2.

Question 7

Mathematics · 4 marks · −1

Consider the relations R1R_1 and R2R_2 defined as aR1b⇔a2+b2=1aR_1b\Leftrightarrow a^2+b^2=1 for all a,b∈Ra,b\in\mathbb{R} and (a,b)R2(c,d)⇔a+d=b+c(a,b)R_2(c,d)\Leftrightarrow a+d=b+c for all (a,b),(c,d)∈N×N(a,b),(c,d)\in\mathbb{N}\times\mathbb{N}. Then:

  1. A.Neither R1R_1 nor R2R_2 is an equivalence relation
  2. B.Only R2R_2 is an equivalence relation
  3. C.Only R1R_1 is an equivalence relation
  4. D.R1R_1 and R2R_2 both are equivalence relations

Correct answer: B

Question 8

Mathematics · 4 marks · −1

Let m and n be the coefficients of seventh and thirteenth terms respectively in the expansion of (13x13+12x23)18\left(\frac13x^{\frac13}+\frac{1}{2x^{\frac23}}\right)^{18}. Then (nm)13\left(\frac nm\right)^{\frac13} is:

  1. A.94\frac94
  2. B.49\frac49
  3. C.14\frac14
  4. D.19\frac19

Correct answer: A

Explanation: m=18C6 3−122−6m={}^{18}C_6\,3^{-12}2^{-6}, n=18C12 3−62−12n={}^{18}C_{12}\,3^{-6}2^{-12}; nm=(32)6\frac nm=\left(\frac32\right)^6, cube root 94\frac94.

Question 9

Mathematics · 4 marks · −1

Let the system of equations x+2y+3z=5x+2y+3z=5, 2x+3y+z=92x+3y+z=9, 4x+3y+λz=μ4x+3y+\lambda z=\mu have infinite number of solutions. Then λ+2μ\lambda+2\mu is equal to:

  1. A.28
  2. B.17
  3. C.22
  4. D.15

Correct answer: B

Explanation: Δ=0⇒λ=−13\Delta=0\Rightarrow\lambda=-13; consistency gives μ=15\mu=15.

Question 10

Mathematics · 4 marks · −1

The value of ∫01(2x3−3x2−x+1)13dx\int_0^1(2x^3-3x^2-x+1)^{\frac13}dx is equal to:

  1. A.−1
  2. B.2
  3. C.0
  4. D.1

Correct answer: C

Explanation: The cubic is odd about x=12x=\frac12.

Question 11

Mathematics · 4 marks · −1

Let the locus of the midpoints of the chords of the circle x2+(y−1)2=1x^2+(y-1)^2=1 drawn from the origin intersect the line x+y=1x+y=1 at P and Q. Then, the length of PQ is:

  1. A.1
  2. B.12\frac1{\sqrt2}
  3. C.12\frac12
  4. D.2\sqrt2

Correct answer: B

Explanation: Locus x2+y2−y=0x^2+y^2-y=0 (centre (0,12)(0,\frac12), radius 12\frac12); distance of centre from the line 122\frac1{2\sqrt2}; chord 214−18=122\sqrt{\frac14-\frac18}=\frac1{\sqrt2}.

Question 12

Mathematics · 4 marks · −1

Let f(x)={x−1,x is even,2x,x is odd,f(x)=\begin{cases}x-1, & x\text{ is even,}\\ 2x, & x\text{ is odd,}\end{cases} x∈Nx\in\mathbb{N}. If for some a∈Na\in\mathbb{N}, f(f(f(a)))=21f(f(f(a)))=21, then lim⁡x→a−{∣x∣3a−[xa]}\lim_{x\to a^-}\left\{\frac{|x|^3}{a}-\left[\frac xa\right]\right\}, where [t] denotes the greatest integer less than or equal to t, is equal to:

  1. A.225
  2. B.121
  3. C.169
  4. D.144

Correct answer: D

Explanation: a=12a=12 (12→11→22→2112\to11\to22\to21); limit 172812−0=144\frac{1728}{12}-0=144.

Question 13

Mathematics · 4 marks · −1

Let f(x)=∣2x2+5∣x∣−3∣f(x)=\left|2x^2+5|x|-3\right|, x∈Rx\in\mathbb{R}. If m and n denote the number of points where f is not continuous and not differentiable respectively, then m + n is equal to:

  1. A.5
  2. B.2
  3. C.0
  4. D.3

Correct answer: D

Explanation: Continuous everywhere; non-differentiable at x=0,±12x=0,\pm\frac12.

Question 14

Mathematics · 4 marks · −1

If the domain of the function f(x)=x2−25(4−x2)+log⁡10(x2+2x−15)f(x)=\frac{\sqrt{x^2-25}}{(4-x^2)}+\log_{10}(x^2+2x-15) is (−∞,α)∪[β,∞)(-\infty,\alpha)\cup[\beta,\infty), then α2+β3\alpha^2+\beta^3 is equal to:

  1. A.150
  2. B.175
  3. C.125
  4. D.140

Correct answer: A

Explanation: Domain (−∞,−5)∪[5,∞)(-\infty,-5)\cup[5,\infty): 25+12525+125.

Question 15

Mathematics · 4 marks · −1

If ∫0π/3cos⁡4x dx=aπ+b3\int_0^{\pi/3}\cos^4x\,dx=a\pi+b\sqrt3, where a and b are rational numbers, then 9a + 8b is equal to:

  1. A.2
  2. B.1
  3. C.32\frac32
  4. D.3

Correct answer: A

Explanation: cos⁡4x=38+12cos⁡2x+18cos⁡4x\cos^4x=\frac38+\frac12\cos2x+\frac18\cos4x; ∫0π/3=π8+38−364\int_0^{\pi/3}=\frac\pi8+\frac{\sqrt3}{8}-\frac{\sqrt3}{64}, so a=18a=\frac18, b=764b=\frac7{64}, 9a+8b=29a+8b=2.

Question 16

Mathematics · 4 marks · −1

Let SnS_n denote the sum of the first n terms of an arithmetic progression. If S10=390S_{10}=390 and the ratio of the tenth and the fifth terms is 15 : 7, then S15−S5S_{15}-S_5 is equal to:

  1. A.790
  2. B.690
  3. C.800
  4. D.890

Correct answer: A

Explanation: a=3a=3, d=8d=8; 885−95=790885-95=790.

Question 17

Mathematics · 4 marks · −1

Let P be a point on the ellipse x29+y24=1\frac{x^2}{9}+\frac{y^2}{4}=1. Let the line passing through P and parallel to y-axis meet the circle x2+y2=9x^2+y^2=9 at point Q such that P and Q are on the same side of the x-axis. Then, the eccentricity of the locus of the point R on PQ such that PR : RQ = 4 : 3 as P moves on the ellipse, is:

  1. A.1321\frac{13}{21}
  2. B.13923\frac{\sqrt{139}}{23}
  3. C.137\frac{\sqrt{13}}{7}
  4. D.1119\frac{11}{19}

Correct answer: C

Explanation: R=(3cos⁡θ,6+127sin⁡θ)R=(3\cos\theta,\frac{6+12}{7}\sin\theta): ellipse with b=187b=\frac{18}{7}, e2=1−3649e^2=1-\frac{36}{49}.

Question 18

Mathematics · 4 marks · −1

Consider a ΔABC where A(1, 3, 2), B(–2, 8, 0) and C(3, 6, 7). If the angle bisector of ∠BAC meets the line BC at D, then the length of the project of the vector AD⃗\vec{AD} on the vector AC⃗\vec{AC} is:

  1. A.382\frac{\sqrt{38}}{2}
  2. B.19\sqrt{19}
  3. C.39238\frac{39}{2\sqrt{38}}
  4. D.37238\frac{37}{2\sqrt{38}}

Correct answer: D

Explanation: AB=AC=38AB=AC=\sqrt{38}, DD = midpoint (12,7,72)(\frac12,7,\frac72); AD⃗⋅AC⃗∣AC∣=37238\vec{AD}\cdot\frac{\vec{AC}}{|AC|}=\frac{37}{2\sqrt{38}}.

Question 19

Mathematics · 4 marks · −1

The lines L1,L2,…,L20L_1,L_2,\ldots,L_{20} are distinct. For n = 1, 2, 3, ...., 10 all the lines L2n−1L_{2n-1} are parallel to each other and all the lines L2nL_{2n} pass through a given P. The maximum number of points of intersection of pairs of lines form the set {L1,L2,…,L20}\{L_1,L_2,\ldots,L_{20}\} is equal to ______.

Correct answer: 101

Explanation: 20C2−10C2−10C2+1=101^{20}C_2-{}^{10}C_2-{}^{10}C_2+1=101.

Question 20

Mathematics · 4 marks · −1

Let a⃗=i^+j^+k^\vec a=\hat i+\hat j+\hat k, b⃗=−i^−8j^+2k^\vec b=-\hat i-8\hat j+2\hat k and c⃗=4i^+c2j^+c3k^\vec c=4\hat i+c_2\hat j+c_3\hat k be three vectors such that b⃗×a⃗=c⃗×a⃗\vec b\times\vec a=\vec c\times\vec a. If the angle between vector c⃗\vec c and the vector 3i^+4j^+k^3\hat i+4\hat j+\hat k is θ, then the greatest integer less than or equal to tan⁡2θ\tan^2\theta is ______.

Correct answer: 38

Explanation: c⃗=b⃗+5a⃗=(4,−3,7)\vec c=\vec b+5\vec a=(4,-3,7); cos⁡θ=77426\cos\theta=\frac{7}{\sqrt{74}\sqrt{26}}; tan⁡2θ=192449−1≈38.3\tan^2\theta=\frac{1924}{49}-1\approx38.3.

Question 21

Mathematics · 4 marks · −1

If dxdy=1+x−y2y\frac{dx}{dy}=\frac{1+x-y^2}{y}, x(1)=1x(1)=1, then 5x(2)5x(2) is equal to ______.

Correct answer: 5

Explanation: ddy(xy)=1y2−1\frac{d}{dy}\left(\frac xy\right)=\frac1{y^2}-1: xy=−1y−y+3\frac xy=-\frac1y-y+3; x(2)=−1−4+6=1x(2)=-1-4+6=1.

Question 22

Mathematics · 4 marks · −1

Let f:(0,∞)→Rf:(0,\infty)\to\mathbb{R} and F(x)=∫0xtf(t)dtF(x)=\int_0^xtf(t)dt. If F(x2)=x4+x5F(x^2)=x^4+x^5, then ∑r=112f(r2)\sum_{r=1}^{12}f(r^2) is equal to ______.

Correct answer: 219

Explanation: 2x3f(x2)=4x3+5x4⇒f(r2)=2+52r2x^3f(x^2)=4x^3+5x^4\Rightarrow f(r^2)=2+\frac52r; sum =24+195=219=24+195=219.

Question 23

Mathematics · 4 marks · −1

Three points O(0, 0), P(a, a²), Q(–b, b²), a > 0, b > 0, are on the parabola y=x2y=x^2. Let S1S_1 be the area of the region bounded by the line PQ and the parabola, and S2S_2 be the area of the triangle OPQ. If the minimum value of S1S2\frac{S_1}{S_2} is mn\frac mn, gcd(m, n) = 1, then m + n is equal to ______.

Correct answer: 7

Explanation: S1=(a+b)36S_1=\frac{(a+b)^3}{6}, S2=ab(a+b)2S_2=\frac{ab(a+b)}{2}; ratio (a+b)23ab≥43\frac{(a+b)^2}{3ab}\ge\frac43.

Question 24

Mathematics · 4 marks · −1

Let A=I2−2MMTA=I_2-2MM^T where M is a real matrix of order 2 × 1 such that the relation MTM=I1M^TM=I_1 holds. If λ is a real number such that the relation AX=λXAX=\lambda X holds for some non-zero real matrix X of order 2 × 1, then the sum of squares of all possible values of λ is equal to ______.

Correct answer: 2

Explanation: AA is a reflection: eigenvalues ±1\pm1.

Question 25

Mathematics · 4 marks · −1

The sum of squares of all possible values of k, for which area of the region bounded by the parabolas 2y2=kx2y^2=kx and ky2=2(y−x)ky^2=2(y-x) is maximum, is equal to ______.

Correct answer: 8

Question 26

Mathematics · 4 marks · −1

If three successive terms of G.P. with common ration r (r > 1) are the lengths of the sides of a triangle and [r] denotes the greatest integer less than or equal to r, then 3[r] + [–r] is equal to ______.

Correct answer: 1

Explanation: 1<r<1+521<r<\frac{1+\sqrt5}{2}: 3(1)+(−2)=13(1)+(-2)=1.

Question 27

Mathematics · 4 marks · −1

If y=(x+1)(x2−x)xx+x+x+115(3cos⁡2x−5)cos⁡3xy=\frac{(\sqrt x+1)(x^2-\sqrt x)}{x\sqrt x+x+\sqrt x}+\frac1{15}(3\cos^2x-5)\cos^3x, then 96y′(π6)96y'\left(\frac\pi6\right) is equal to ______.

Correct answer: 105

Explanation: y=x−1+115(3cos⁡5x−5cos⁡3x)y=x-1+\frac1{15}(3\cos^5x-5\cos^3x), y=ˊ1+sin⁡3xcos⁡2xy\'=1+\sin^3x\cos^2x; 96y(ˊπ6)=96+9=10596y\'(\frac\pi6)=96+9=105.

Question 28

Mathematics · 4 marks · −1

Let ABC be an isosceles triangle in which A is at (–1, 0), ∠A=2π3\angle A=\frac{2\pi}{3}, AB = AC and B is on the positive x-axis. If BC=43BC=4\sqrt3 and the line BC intersects the line y=x+3y=x+3 at (α,β)(\alpha,\beta) then β4α2\frac{\beta^4}{\alpha^2} is ______.

Correct answer: 36

Question 29

Physics · 4 marks · −1

Conductivity of a photodiode starts changing only if the wavelength of incident light is less than 660 nm. The band gap of photodiode is found to be (X8)\left(\frac X8\right) eV. The value of X is: (Given, h = 6.6×10−346.6\times10^{-34} J s, e = 1.6×10−191.6\times10^{-19} C)

  1. A.11
  2. B.13
  3. C.21
  4. D.15

Correct answer: D

Explanation: E=hcλe=1.875E=\frac{hc}{\lambda e}=1.875 eV =158=\frac{15}{8}.

Question 30

Physics · 4 marks · −1

A diatomic gas (γ = 1.4) does 200 J of work when it is expanded isobarically. The heat given to the gas in the process is:

  1. A.700 J
  2. B.600 J
  3. C.800 J
  4. D.850 J

Correct answer: A

Explanation: Q=γγ−1W=3.5×200Q=\frac{\gamma}{\gamma-1}W=3.5\times200.

Question 31

Physics · 4 marks · −1

In an ammeter, 5% of the main current passes through the galvanometer. If resistance of the galvanometer is G, the resistance of ammeter will be:

  1. A.G20\frac{G}{20}
  2. B.G199\frac{G}{199}
  3. C.199G199G
  4. D.200G200G

Correct answer: A

Explanation: Shunt S=G19S=\frac{G}{19}; GSG+S=G20\frac{GS}{G+S}=\frac G{20}.

Question 32

Physics · 4 marks · −1

A galvanometer (G) of 2Ω resistance is connected in the given circuit. The ratio of charge stored in C1C_1 and C2C_2 is:

Figure for question 32
  1. A.1
  2. B.12\frac12
  3. C.32\frac32
  4. D.23\frac23

Correct answer: B

Explanation: Steady current flows 4 Ω → G → 6 Ω: I=0.5I=0.5 A. VC1V_{C_1} = drop across 4 Ω + G = 3 V, VC2V_{C_2} = drop across G + 6 Ω = 4 V; Q1Q2=4×36×4=12\frac{Q_1}{Q_2}=\frac{4\times3}{6\times4}=\frac12.

Question 33

Physics · 4 marks · −1

From the statements given below: (A) The angular momentum of an electron in nthn^{th} orbit is an integral multiple of ħ. (B) Nuclear forces do not obey inverse square law. (C) Nuclear forces are spin dependent. (D) Nuclear forces are central and charge independent. (E) Stability of nucleus is inversely proportional to the value of packing fraction. Choose the correct answer from the options given below:

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

Correct answer: B

Explanation: Nuclear forces are non-central.

Question 34

Physics · 4 marks · −1

A body of mass 4 kg experiences two forces F⃗1=5i^+8j^+7k^\vec F_1=5\hat i+8\hat j+7\hat k and F⃗2=3i^−4j^−3k^\vec F_2=3\hat i-4\hat j-3\hat k. The acceleration acting on the body is:

  1. A.4i^+2j^+2k^4\hat i+2\hat j+2\hat k
  2. B.2i^+j^+k^2\hat i+\hat j+\hat k
  3. C.2i^+3j^+3k^2\hat i+3\hat j+3\hat k
  4. D.−2i^−j^−k^-2\hat i-\hat j-\hat k

Correct answer: B

Question 35

Physics · 4 marks · −1

A disc of radius R and mass M is rolling horizontally without slipping with speed v. It then moves up an inclined smooth surface as shown in figure. The maximum height that the disc can go up the incline is:

Figure for question 35
  1. A.34v2g\frac34\frac{v^2}{g}
  2. B.v2g\frac{v^2}{g}
  3. C.12v2g\frac12\frac{v^2}{g}
  4. D.23v2g\frac23\frac{v^2}{g}

Correct answer: C

Explanation: On a smooth incline the spin is unchanged; only translational KE converts: h=v22gh=\frac{v^2}{2g}.

Question 36

Physics · 4 marks · −1

In a metre-bridge when a resistance in the left gap is 2Ω and unknown resistance in the right gap, the balance length is found to be 40 cm. On shunting the unknown resistance with 2Ω, the balance length changes by:

  1. A.22.5 cm
  2. B.62.5 cm
  3. C.65 cm
  4. D.20 cm

Correct answer: A

Explanation: X=3 ΩX=3\ \Omega; 3∥2=1.2 Ω3\parallel2=1.2\ \Omega; new balance 62.5 cm, change 22.5 cm.

Question 37

Physics · 4 marks · −1

A cricket player catches a ball of mass 120 g moving with 25 m/s speed. If the catching process is completed in 0.1 s then the magnitude of force exerted by the ball on the hand of player will be: (in SI unit):

  1. A.12
  2. B.30
  3. C.25
  4. D.24

Correct answer: B

Question 38

Physics · 4 marks · −1

If frequency of electromagnetic wave is 60 MHz and it travels in air along z direction then the corresponding electric and magnetic field vectors will be mutually perpendicular to each other and the wavelength of the wave (in m) is:

  1. A.10
  2. B.2.5
  3. C.5
  4. D.2

Correct answer: C

Question 39

Physics · 4 marks · −1

C1C_1 and C2C_2 are two hollow concentric cubes enclosing charges 2Q and 3Q respectively as shown in figure. The ratio of electric flux passing through C1C_1 and C2C_2 is:

Figure for question 39
  1. A.2 : 5
  2. B.3 : 2
  3. C.2 : 3
  4. D.5 : 2

Correct answer: A

Explanation: C1C_1 encloses 2Q, C2C_2 encloses 5Q.

Question 40

Physics · 4 marks · −1

Train A is moving along two parallel rail tracks towards north with speed 72 km/h and train B is moving towards south with speed 108 km/h. Velocity of train B with respect to A and velocity of ground with respect to B are (in m s−1^{-1}):

  1. A.−50 and −30
  2. B.−50 and 30
  3. C.50 and −30
  4. D.−30 and 50

Correct answer: B

Question 41

Physics · 4 marks · −1

A microwave of wavelength 2.0 cm falls normally on a slit of width 4.0 cm. The angular spread of the central maxima of the diffraction pattern obtained on a screen 1.5 m away from the slit, will be:

  1. A.45°
  2. B.60°
  3. C.30°
  4. D.15°

Correct answer: B

Explanation: sin⁡θ=12\sin\theta=\frac12; spread 2θ=60∘2\theta=60^\circ.

Question 42

Physics · 4 marks · −1

A light planet is revolving around a massive star in a circular orbit of radius R with a period of revolution T. If the force of attraction between planet and star is proportional to R−3/2R^{-3/2} then chose the correct option:

  1. A.T2∝R7/2T^2\propto R^{7/2}
  2. B.T2∝R5/2T^2\propto R^{5/2}
  3. C.T2∝R3T^2\propto R^3
  4. D.T2∝R3/2T^2\propto R^{3/2}

Correct answer: B

Explanation: mω2R∝R−3/2⇒T2∝R5/2m\omega^2R\propto R^{-3/2}\Rightarrow T^2\propto R^{5/2}.

Question 43

Physics · 4 marks · −1

If the root mean square velocity of hydrogen molecule at a given temperature and pressure is 2 km/s, the root mean square velocity of oxygen at the same condition in km/s is:

  1. A.0.5
  2. B.1.0
  3. C.1.5
  4. D.2.0

Correct answer: A

Question 44

Physics · 4 marks · −1

A big drop is formed by coalescing 1000 small droplets of water. The surface energy will become:

  1. A.100 times
  2. B.1100\frac1{100}th
  3. C.10 times
  4. D.110\frac1{10}th

Correct answer: D

Question 45

Physics · 4 marks · −1

To measure the temperature coefficient of resistivity α of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25° and resistance of the semiconductor arm is 3 mΩ. Arm BC is cooled at a constant rate of 2°C/s. If the galvanometer G shows no deflection after 10 s. then α is:

Figure for question 45
  1. A.−1.5×10−2-1.5\times10^{-2} °C−1^{-1}
  2. B.−2×10−2-2\times10^{-2} °C−1^{-1}
  3. C.−1×10−2-1\times10^{-2} °C−1^{-1}
  4. D.−2.5×10−2-2.5\times10^{-2} °C−1^{-1}

Correct answer: C

Explanation: Balance needs RBC=3×0.81=2.4R_{BC}=\frac{3\times0.8}{1}=2.4 mΩ after 10 s (20 °C of cooling): ∣α∣=0.63×20=10−2|\alpha|=\frac{0.6}{3\times20}=10^{-2} /°C; the keyed option carries the negative sign expected for a semiconductor.

Question 46

Physics · 4 marks · −1

Match List-I with List-II. List-I (Number): (A) 1001; (B) 010.1; (C) 100.100; (D) 0.0010010 List-II (Significant figure): (I) 3; (II) 4; (III) 5; (IV) 6 Choose the correct answer from the options given below:

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

Correct answer: C

Question 47

Physics · 4 marks · −1

Monochromatic light of frequency 6×10146\times10^{14} Hz is produced by a laser. The power emitted is 2×10−32\times10^{-3} W. How many photons per second on an average, are emitted by the source?

  1. A.7×10167\times10^{16}
  2. B.9×10189\times10^{18}
  3. C.6×10156\times10^{15}
  4. D.5×10155\times10^{15}

Correct answer: D

Question 48

Physics · 4 marks · −1

A transformer has an efficiency of 80% and works at 10 V and 4 kW. If the secondary voltage is 240 V, then the current in the secondary coil is:

  1. A.1.59 A
  2. B.13.33 A
  3. C.1.33 A
  4. D.15.1 A

Correct answer: B

Explanation: 0.8×4000240=13.33\frac{0.8\times4000}{240}=13.33 A.

Question 49

Physics · 4 marks · −1

In an electrical circuit drawn below the amount of charge stored in the capacitor is ______ μC.

Figure for question 49

Correct answer: 60

Explanation: Current 1010=1\frac{10}{10}=1 A through R1R_1 and R3R_3; the capacitor branch sees 6 V: Q=60Q=60 μC.

Question 50

Physics · 4 marks · −1

A particle initially at rest starts moving from reference point x = 0 along x-axis, with velocity v that varies as v=4xv=4\sqrt x m/s. The acceleration of the particle is ______ m s−2^{-2}.

Correct answer: 8

Explanation: a=vdvdx=8a=v\frac{dv}{dx}=8.

Question 51

Physics · 4 marks · −1

A mass m is suspended from a spring of negligible mass and the system oscillates with a frequency f1f_1. The frequency of oscillations if a mass 9 m is suspended from the same spring is f2f_2. The value of f1f2\frac{f_1}{f_2} is ______.

Correct answer: 3

Question 52

Physics · 4 marks · −1

One end of a metal wire is fixed to a ceiling and a load of 2 kg hands from the other end. A similar wire is attached to the bottom of the load and anther load of 1 kg hangs from this lower wire. Then the ratio of longitudinal strain of upper wire to that of the lower wire will be ______. [Area of cross section of wire = 0.005 cm²; Y = 2×10112\times10^{11} N m−2^{-2} and g = 10 m s−2^{-2}]

Correct answer: 3

Explanation: Tensions 30 N and 10 N.

Question 53

Physics · 4 marks · −1

A coil of 200 turns and area 0.20 m² is rotated at half a revolution per second and is placed in uniform magnetic field of 0.01 T perpendicular to axis of rotation of the coil. The maximum voltage generated in the coil is 2πβ\frac{2\pi}{\beta} volt. The value of β is ______.

Correct answer: 5

Explanation: NBAω=200(0.01)(0.2)π=2π5NBA\omega=200(0.01)(0.2)\pi=\frac{2\pi}{5}.

Question 54

Physics · 4 marks · −1

A moving coil galvanometer has 100 turns and each has an area of 2.0 cm². The magnetic field produced by the magnet is 0.01 T and the deflection in the coil is 0.05 radian when a current of 10 mA is passed through it. The torsional constant of the suspension wire is x×10−5x\times10^{-5} N-m/rad. The value of x is ______.

Correct answer: 4

Explanation: k=NBAIθ=4×10−5k=\frac{NBAI}{\theta}=4\times10^{-5}.

Question 55

Physics · 4 marks · −1

A uniform rod AB of mass 2 kg and length 30 cm at rest on a smooth horizontal surface. An impulse of force 0.2 Ns is applied to end B. The time taken by the rod to turn through at right angles will be πx\frac\pi x s, where x = ______.

Correct answer: 4

Explanation: JL2=ML212ω⇒ω=6JML=2J\frac L2=\frac{ML^2}{12}\omega\Rightarrow\omega=\frac{6J}{ML}=2 rad/s; t=π/22=π4t=\frac{\pi/2}{2}=\frac\pi4.

Question 56

Physics · 4 marks · −1

A particular hydrogen - like ion emits the radiation of frequency 3×10153\times10^{15} Hz when it makes transition from n = 2 to n = 1. The frequency of radiation emitted in transition from n = 3 to n = 1 is x9×1015\frac x9\times10^{15} Hz, when x = ______.

Correct answer: 32

Explanation: 3×8/93/4=3293\times\frac{8/9}{3/4}=\frac{32}{9}.

Question 57

Physics · 4 marks · −1

In Yong's double slit experiment, monochromatic light of wavelength 5000 Å is used. The slits are 1.0 mm apart and screen is placed at 1.0 m away from slits. The distance from the centre of the screen where intensity becomes half of the maximum intensity for the first time is ______ ×10−6\times10^{-6} m.

Correct answer: 125

Explanation: Phase π2\frac\pi2: y=λD4d=125×10−6y=\frac{\lambda D}{4d}=125\times10^{-6} m.

Question 58

Physics · 4 marks · −1

Suppose a uniformly charged wall provides a uniform electric field of 2×1042\times10^4 N/C normally. A charged particle of mass 2 g being suspended through a silk thread of length 20 cm and remain stayed at a distance of 10 cm from the wall. Then the charge on the particle will be 1x\frac1{\sqrt x} μC where x = ______. [use g = 10 m/s²]

Correct answer: 3

Explanation: tan⁡θ=13\tan\theta=\frac{1}{\sqrt3}; q=mgtan⁡θE=0.023×2×104=13q=\frac{mg\tan\theta}{E}=\frac{0.02}{\sqrt3\times2\times10^4}=\frac{1}{\sqrt3} μC.

Question 59

Chemistry · 4 marks · −1

Given below are two statements: Statement (I): Both metals and non-metals exist in p and d-block elements. Statement (II): Non-metals have higher ionization enthalpy and higher electronegativity than the metals. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Statements I is true but Statement II is false
  2. B.Statement I is false but Statement II is true
  3. C.Both Statement I and Statement II are true
  4. D.Both Statement I and Statement II are false

Correct answer: B

Explanation: d-block contains only metals.

Question 60

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): In aqueous solutions Cr2+\text{Cr}^{2+} is reducing while Mn3+\text{Mn}^{3+} is oxidizing in nature. Reason (R): Extra stability to half filled electronic configuration is observed than incompletely filled electronic configuration. In the light of the above statements, choose the most appropriate answer from the options given below:

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

Correct answer: C

Question 61

Chemistry · 4 marks · −1

Given below are two statements: Statement (I): SiO2\text{SiO}_2 and GeO2\text{GeO}_2 are acidic while SnO and PbO are amphoteric in nature. Statement (II): Allotropic forms of carbon are due to property of catenation and pπ-dπ bond formation. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Statements I is true but Statement II is false
  2. B.Both Statement I and Statement II are false
  3. C.Statement I is false but Statement II is true
  4. D.Both Statement I and Statement II are true

Correct answer: A

Explanation: Carbon allotropy involves pπ–pπ bonding.

Question 62

Chemistry · 4 marks · −1

The number of radial node/s for 3p orbital is:

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

Correct answer: D

Explanation: n−l−1=1n-l-1=1.

Question 63

Chemistry · 4 marks · −1

Solubility of calcium phosphate (molecular mass, M) in water is WgW_g per 100 mL at 25 °C. Its solubility product at 25 °C will be approximately.

  1. A.107(WM)310^7\left(\frac WM\right)^3
  2. B.107(WM)510^7\left(\frac WM\right)^5
  3. C.103(WM)510^3\left(\frac WM\right)^5
  4. D.105(WM)510^5\left(\frac WM\right)^5

Correct answer: B

Explanation: s=10WMs=\frac{10W}{M} mol/L; Ksp=108s5≈107(WM)5K_{sp}=108s^5\approx10^7\left(\frac WM\right)^5.

Question 64

Chemistry · 4 marks · −1

Match List-I with List-II. List-I (Compound): (A) Carbon tetrachloride; (B) Methylene chloride; (C) DDT; (D) Freons List-II (Use): (I) Paint remover; (II) Refrigerators and air conditioners; (III) Fire extinguisher; (IV) Non Biodegradable insecticide Choose the correct answer from the options given below:

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

Correct answer: D

Question 65

Chemistry · 4 marks · −1

The functional group that shows negative resonance effect is:

  1. A.–OR
  2. B.–OH
  3. C.–COOH
  4. D.–NH2_2

Correct answer: C

Question 66

Chemistry · 4 marks · −1

[Co(NH3)6]3+[\text{Co(NH}_3)_6]^{3+} and [CoF6]3−[\text{CoF}_6]^{3-} are respectively known as:

  1. A.Inner orbital complex, Spin paired Complex
  2. B.Spin paired Complex, Spin free Complex
  3. C.Outer orbital Complex Inner orbital Complex
  4. D.Spin free Complex, Spin paired Complex

Correct answer: B

Question 67

Chemistry · 4 marks · −1

Which of the following compounds show colour due to d-d transition?

  1. A.K2CrO4\text{K}_2\text{CrO}_4
  2. B.K2Cr2O7\text{K}_2\text{Cr}_2\text{O}_7
  3. C.CuSO4⋅5H2O\text{CuSO}_4\cdot5\text{H}_2\text{O}
  4. D.KMnO4\text{KMnO}_4

Correct answer: C

Question 68

Chemistry · 4 marks · −1

Lassaigne's test is used for detection of :

  1. A.Phosphorous and halogens only
  2. B.Nitrogen, Sulphur and Phosphorous only
  3. C.Nitrogen, Sulphur and halogens
  4. D.Nitrogen and Sulphur only

Correct answer: C

Question 69

Chemistry · 4 marks · −1

Select the compound from the following that will show intramolecular hydrogen bonding.

  1. A.C2H5OH\text{C}_2\text{H}_5\text{OH}
  2. B.o-Nitrophenol
  3. C.NH3\text{NH}_3
  4. D.H2O\text{H}_2\text{O}

Correct answer: B

Question 70

Chemistry · 4 marks · −1

In the given reaction identify A and B H2+A→Pd/C\text{H}_2+A\xrightarrow{\text{Pd/C}} cis-CH3CH=CHC2H5\text{CH}_3\text{CH=CHC}_2\text{H}_5 (cis-pent-2-ene) CH3-C≡C-CH3+H2→Na/Liquid NH3\text{CH}_3\text{-C}\equiv\text{C-CH}_3+\text{H}_2\xrightarrow{\text{Na/Liquid NH}_3} "B"

  1. A.A : 2 – Pentyne, B : Cis – 2 – butene
  2. B.A : n – Pentane, B : Cis – 2 – butene
  3. C.A : 2 – Pentyne, B : trans – 2 – butene
  4. D.A : n – Pentane, B : trans – 2 – butene

Correct answer: C

Question 71

Chemistry · 4 marks · −1

The set of meta directing functional groups from the following sets is:

  1. A.–NO2_2, –CHO, –SO3_3H, –COR
  2. B.–CN, –NH2_2, –NHR, –OCH3_3
  3. C.–CN, –CHO, –NHCOCH3_3, –COOR
  4. D.–NO2_2, –NH2_2, –COOH, –COOR

Correct answer: A

Question 72

Chemistry · 4 marks · −1

Which among the following has highest boiling point?

  1. A.H5C2-O-C2H5\text{H}_5\text{C}_2\text{-O-C}_2\text{H}_5
  2. B.CH3CH2CH2CH3\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_3
  3. C.CH3CH2CH2CHO\text{CH}_3\text{CH}_2\text{CH}_2\text{CHO}
  4. D.CH3CH2CH2CH2-OH\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{-OH}

Correct answer: D

Question 73

Chemistry · 4 marks · −1

Given below are two statements: Statement (I): A π bonding MO has lower electron density above and below the inter-nuclear axis. Statement (II): The π* antibonding MO has a node between the nuclei. 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 true
  2. B.Statements I is true but Statement II is false
  3. C.Statement I is false but Statement II is true
  4. D.Both Statement I and Statement II are false

Correct answer: C

Question 74

Chemistry · 4 marks · −1

The transition metal having highest 3rd ionisation enthalpy is:

  1. A.V
  2. B.Fe
  3. C.Mn
  4. D.Cr

Correct answer: C

Explanation: Mn2+^{2+} is d5^5.

Question 75

Chemistry · 4 marks · −1

C2H5Br→alc. KOHA→Br2/CCl4B→KCN (Excess)C→H3O+ (Excess)D\text{C}_2\text{H}_5\text{Br}\xrightarrow{\text{alc. KOH}}A\xrightarrow{\text{Br}_2/\text{CCl}_4}B\xrightarrow{\text{KCN (Excess)}}C\xrightarrow{\text{H}_3\text{O}^+\text{ (Excess)}}D. Acid D formed in above reaction is:

  1. A.Succinic acid
  2. B.Oxalic acid
  3. C.Gluconic acid
  4. D.Malonic acid

Correct answer: A

Question 76

Chemistry · 4 marks · −1

Given below are two statements: Statement (I): Dimethyl glyoxime forms a six-membered covalent chelate when treated with NiCl2\text{NiCl}_2 solution in presence of NH4OH\text{NH}_4\text{OH}. Statement (II): Prussian blue precipitate contains ion both in (+2) and (+3) oxidation states. In the light of the above statements, choose the most appropriate answer from the options given below:

  1. A.Statements I is true but Statement II is false
  2. B.Both Statement I and Statement II are false
  3. C.Both Statement I and Statement II are true
  4. D.Statement I is false but Statement II is true

Correct answer: D

Explanation: Ni(dmg)2_2 rings are five-membered.

Question 77

Chemistry · 4 marks · −1

The strongest reducing agent among the following is:

  1. A.PH3\text{PH}_3
  2. B.NH3\text{NH}_3
  3. C.BiH3\text{BiH}_3
  4. D.SbH3\text{SbH}_3

Correct answer: C

Question 78

Chemistry · 4 marks · −1

Match List-I with List-II. List-I (Reactants): (A) Phenol, Zn/Δ; (B) Phenol, CHCl3\text{CHCl}_3, NaOH, HCl; (C) Phenol, CO2\text{CO}_2, NaOH, HCl; (D) Phenol, Conc. HNO3\text{HNO}_3 List-II (Product): (I) Salicylaldehyde; (II) Salicylic acid; (III) Benzene; (IV) Picric acid Choose the correct answer from the options given below:

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

Correct answer: D

Question 79

Chemistry · 4 marks · −1

Total number of isomeric compounds (including stereoisomers) formed by monochlorination of 2-methylbutane is ______.

Correct answer: 6

Question 80

Chemistry · 4 marks · −1

Mass of ethylene glycol (antifreeze) to be added to 18.6 kg of water to protect the freezing point at –24°C is ______ kg (Molar mass in g mol−1^{-1} for ethylene glycol 62, KfK_f of water = 1.86 K kg mol−1^{-1})

Correct answer: 15

Explanation: m=241.86m=\frac{24}{1.86}; moles =240=240; mass =14.9=14.9 kg ≈ 15.

Question 81

Chemistry · 4 marks · −1

For a certain reaction at 300 K, K = 10, then ΔG° for the same reaction is ______ ×10−1\times10^{-1} kJ mol−1^{-1}. (Given R = 8.314 J K−1^{-1} mol−1^{-1})

Correct answer: 57

Explanation: ΔG∘=−2.303RTlog⁡K=−5.74\Delta G^\circ=-2.303RT\log K=-5.74 kJ/mol.

Question 82

Chemistry · 4 marks · −1

The number of tripeptides formed by three different amino acids using each amino acid once is ______.

Correct answer: 6

Question 83

Chemistry · 4 marks · −1

10 mL of gaseous hydrocarbon on combustion gives 40 mL of CO2\text{CO}_2(g) and 50 mL of water vapour. Total number of carbon and hydrogen atoms in the hydrocarbon is ______.

Correct answer: 14

Explanation: C4H10\text{C}_4\text{H}_{10}.

Question 84

Chemistry · 4 marks · −1

The amount of electricity in Columb required for the oxidation of 1 mol of H2O\text{H}_2\text{O} to O2\text{O}_2 is ______ ×105\times10^5 C.

Correct answer: 2

Explanation: 2 F ≈ 1.93×1051.93\times10^5 C.

Question 85

Chemistry · 4 marks · −1

Number of compounds which give reaction with Hinsberg's reagent is ______.

Figure for question 85

Correct answer: 5

Explanation: Primary and secondary amines: aniline, N-methylbenzylamine, ethylenediamine, piperidine, propylamine.

Question 86

Chemistry · 4 marks · −1

Following Kjeldahl's method, 1g of organic compound released ammonia, that neutralised 10 mL of 2M H2SO4\text{H}_2\text{SO}_4. The percentage of nitrogen in the compound is ______ %.

Correct answer: 56

Explanation: 40 mmol NH3_3 → 0.56 g N.

Question 87

Chemistry · 4 marks · −1

Consider the following redox reaction: MnO4−+H++H2C2O4⇌Mn2++H2O+CO2\text{MnO}_4^-+\text{H}^++\text{H}_2\text{C}_2\text{O}_4\rightleftharpoons\text{Mn}^{2+}+\text{H}_2\text{O}+\text{CO}_2. The standard reduction potentials are given as below: EMnO4−/Mn2+∘=+1.51E^\circ_{\text{MnO}_4^-/\text{Mn}^{2+}}=+1.51 V; ECO2/H2C2O4∘=−0.49E^\circ_{\text{CO}_2/\text{H}_2\text{C}_2\text{O}_4}=-0.49 V. If the equilibrium constant of the above reaction is given as Keq=10xK_{eq}=10^x, then the value of x = ______. (nearest Integer)

Correct answer: 338

Explanation: n=10n=10, E∘=2.00E^\circ=2.00 V; x=10×20.059≈338x=\frac{10\times2}{0.059}\approx338.

Question 88

Chemistry · 4 marks · −1

The following data were obtained during the first order thermal decomposition of a gas A at constant volume: A(g)→2B(g)+C(g)A(g)\to2B(g)+C(g) | S. No. | Time/s | Total pressure/(atm) | | 1. | 0 | 0.1 | | 2. | 115 | 0.28 | The rate constant of the reaction is ______ ×10−2\times10^{-2} s−1^{-1} (nearest integer)

Correct answer: 2

Explanation: PA=3(0.1)−0.282=0.01P_A=\frac{3(0.1)-0.28}{2}=0.01; k=2.303115log⁡10=0.02k=\frac{2.303}{115}\log10=0.02.

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