JEE Main 2024 — 4 Apr Shift 1 (Previous Year Paper)

JEE Main · 2024 · with answers and explanations

questions
85
Total marks
284
Duration
180 minutes
Negative marking
−1

Subjects: Physics · Chemistry · Mathematics

Question 1

Physics · 4 marks · −1

In an experiment to measure focal length (f)(f) of convex lens, the least counts of the measuring scales for the position of object (u)(u) and for the position of image (v)(v) are Δu\Delta u and Δv\Delta v, respectively. The error in the measurement of the focal length of the convex lens will be:

  1. A.2f[Δuu+Δvv]2f\left[\frac{\Delta u}{u}+\frac{\Delta v}{v}\right]
  2. B.Δuu+Δvv\frac{\Delta u}{u}+\frac{\Delta v}{v}
  3. C.f2[Δuu2+Δvv2]f^2\left[\frac{\Delta u}{u^2}+\frac{\Delta v}{v^2}\right]
  4. D.f[Δuu+Δvv]f\left[\frac{\Delta u}{u}+\frac{\Delta v}{v}\right]

Correct answer: C

Explanation: Differentiating 1f=1v−1u\frac1f=\frac1v-\frac1u: Δff2=Δuu2+Δvv2\frac{\Delta f}{f^2}=\frac{\Delta u}{u^2}+\frac{\Delta v}{v^2}.

Question 2

Physics · 4 marks · −1

The equation of stationary wave is: y=2asin⁡(2πntλ)cos⁡(2πxλ)y=2a\sin\left(\frac{2\pi nt}{\lambda}\right)\cos\left(\frac{2\pi x}{\lambda}\right). Which of the following is NOT correct:

  1. A.The dimensions of n/λn/\lambda is [T]
  2. B.The dimensions of nn is [LT−1][LT^{-1}]
  3. C.The dimensions of xx is [L]
  4. D.The dimensions of ntnt is [L]

Correct answer: A

Explanation: nt/λnt/\lambda is dimensionless, so [n]=LT−1[n]=LT^{-1} and [n/λ]=T−1[n/\lambda]=T^{-1}.

Question 3

Physics · 4 marks · −1

A body travels 102.5 m in nthn^{th} second and 115.0 m in (n+2)th(n+2)^{th} second. The acceleration is:

  1. A.6.25 m/s²
  2. B.12.5 m/s²
  3. C.9 m/s²
  4. D.5 m/s²

Correct answer: A

Explanation: sn+2−sn=2a=12.5s_{n+2}-s_n=2a=12.5.

Question 4

Physics · 4 marks · −1

The co-ordinates of a particle moving in x−yx-y plane are given by: x=2+4tx=2+4t, y=3t+8t2y=3t+8t^2. The motion of the particle is:

  1. A.uniformly accelerated having motion along a parabolic path.
  2. B.uniform motion along a straight line.
  3. C.uniformly accelerated having motion along a straight line.
  4. D.non-uniformly accelerated.

Correct answer: A

Explanation: a⃗=16j^\vec a=16\hat j is constant and not parallel to v⃗(0)=(4,3)\vec v(0)=(4,3).

Question 5

Physics · 4 marks · −1

If a rubber ball falls from a height hh and rebounds upto the height of h/2h/2. The percentage loss of total energy of the initial system as well as velocity ball before it strikes the ground, respectively, are:

  1. A.50%, 2gh\sqrt{2gh}
  2. B.50%, gh\sqrt{gh}
  3. C.40%, 2gh\sqrt{2gh}
  4. D.50%, gh2\sqrt{\frac{gh}{2}}

Correct answer: A

Question 6

Physics · 4 marks · −1

A metal wire of uniform mass density having length LL and mass MM is bent to form a semicircular arc and a particle of mass mm is placed at the centre of the arc. The gravitational force on the particle by the wire is:

  1. A.GmMπ2L2\frac{GmM\pi^2}{L^2}
  2. B.GMmπ2L2\frac{GMm\pi}{2L^2}
  3. C.0
  4. D.2GmMπL2\frac{2GmM\pi}{L^2}

Correct answer: D

Explanation: R=L/πR=L/\pi; F=2GmλR=2GmMπL2F=\frac{2G m\lambda}{R}=\frac{2GmM\pi}{L^2}.

Question 7

Physics · 4 marks · −1

Given below are two statements: Statement I : When speed of liquid is zero everywhere, pressure difference at any two points depends on equation P1−P2=ρg(h2−h1)P_1-P_2=\rho g(h_2-h_1). Statement II : In ventury tube shown 2gh=v12−v222gh=v_1^2-v_2^2. In the light of the above statements, choose the most appropriate answer from the options given below.

Figure for question 7
  1. A.Both Statement I and Statement II are correct.
  2. B.Statement I is correct but Statement II is incorrect.
  3. C.Statement I is incorrect but Statement II is correct.
  4. D.Both Statement I and Statement II are incorrect.

Correct answer: B

Explanation: Flow is faster at the throat: 2gh=v22−v122gh=v_2^2-v_1^2.

Question 8

Physics · 4 marks · −1

The resistances of the platinum wire of a platinum resistance thermometer at the ice point and steam point are 8Ω and 10Ω respectively. After inserting in a hot bath of temperature 400°C, the resistance of platinum wire is:

  1. A.10Ω
  2. B.8Ω
  3. C.16Ω
  4. D.2Ω

Correct answer: C

Explanation: R=8+2100×400=16 ΩR=8+\frac{2}{100}\times400=16\ \Omega.

Question 9

Physics · 4 marks · −1

On celcius scale the temperature of body increases by 40°C. The increase in temperature on Fahrenheit scale is:

  1. A.68°F
  2. B.75°F
  3. C.72°F
  4. D.70°F

Correct answer: C

Question 10

Physics · 4 marks · −1

P-T diagram of an ideal gas having three different densities ρ1,ρ2,ρ3\rho_1,\rho_2,\rho_3 (in three different cases) is shown in the figure. Which of the following is correct:

Figure for question 10
  1. A.ρ1>ρ2\rho_1>\rho_2
  2. B.ρ2<ρ3\rho_2<\rho_3
  3. C.ρ1=ρ2=ρ3\rho_1=\rho_2=\rho_3
  4. D.ρ1<ρ2\rho_1<\rho_2

Correct answer: A

Explanation: P=ρRTMP=\frac{\rho RT}{M}: slope ∝ ρ.

Question 11

Physics · 4 marks · −1

An infinitely long positively charged straight thread has a linear charge density λ C/m. An electron revolves along a circular path having axis along the length of the wire. The graph that correctly represents the variation of the kinetic energy of electron as a function of radius of circular path from the wire is:

Figure for question 11
  1. A.KE increases linearly with r
  2. B.KE decreases (hyperbola-like) with r
  3. C.KE constant (horizontal line)
  4. D.KE increases non-linearly with r

Correct answer: C

Explanation: mv2r=eλ2πϵ0r\frac{mv^2}{r}=\frac{e\lambda}{2\pi\epsilon_0r}, so KE is independent of r.

Question 12

Physics · 4 marks · −1

To measure the internal resistance of a battery, potentiometer is used. For R = 10Ω, the balance point is observed at ll = 500 cm and for R = 1Ω the balance point is observed at ll = 400 cm. The internal resistance of the battery is approximately:

  1. A.0.2Ω
  2. B.0.3Ω
  3. C.0.4Ω
  4. D.0.1Ω

Correct answer: B

Explanation: 10(1+r)10+r=54⇒r≈0.29 Ω\frac{10(1+r)}{10+r}=\frac54\Rightarrow r\approx0.29\ \Omega.

Question 13

Physics · 4 marks · −1

An electron is projected with uniform velocity along the axis inside a current carrying long solenoid. Then:

  1. A.the electron will continue to move with uniform velocity along the axis of the solenoid.
  2. B.the electron will be accelerated along the axis.
  3. C.the electron path will be circular about the axis.
  4. D.the electron will experience a force at 45° to the axis and execute a helical path.

Correct answer: A

Question 14

Physics · 4 marks · −1

In an ac circuit, the instantaneous current is zero, when the instantaneous voltage is maximum. In this case, the source may be connected to: A. pure inductor. B. pure capacitor. C. pure resistor. D. combination of an inductor and capacitor. Choose the correct answer from the options given below:

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

Correct answer: D

Question 15

Physics · 4 marks · −1

The electric field in an electromagnetic wave is given by E⃗=i^40cos⁡ω(t−z/c)\vec E=\hat i40\cos\omega(t-z/c) N C−1^{-1}. The magnetic field induction of this wave is (in SI unit):

  1. A.B⃗=k^40ccos⁡ω(t−z/c)\vec B=\hat k\frac{40}{c}\cos\omega(t-z/c)
  2. B.B⃗=j^40cos⁡ω(t−z/c)\vec B=\hat j40\cos\omega(t-z/c)
  3. C.B⃗=i^40ccos⁡ω(t−z/c)\vec B=\hat i\frac{40}{c}\cos\omega(t-z/c)
  4. D.B⃗=j^40ccos⁡ω(t−z/c)\vec B=\hat j\frac{40}{c}\cos\omega(t-z/c)

Correct answer: D

Question 16

Physics · 4 marks · −1

An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is 25D. Focal length of each of the convex lens is:

  1. A.20 cm
  2. B.50 cm
  3. C.500 cm
  4. D.25 cm

Correct answer: A

Question 17

Physics · 4 marks · −1

Which figure shows the correct variation of applied potential difference (V) with photoelectric current (I) at two different intensities of light (I1<I2)(I_1<I_2) of same wavelengths:

Figure for question 17
  1. A.Curves for I1I_1 and I2I_2 with different cut-off voltages
  2. B.Both curves start at the same stopping potential −V0-V_0; I2I_2 saturates higher than I1I_1
  3. C.Curves with different stopping potentials, I2I_2 higher
  4. D.Both from −V0-V_0 with I1I_1 and I2I_2 crossing

Correct answer: B

Explanation: Stopping potential depends only on frequency; saturation current ∝ intensity.

Question 18

Physics · 4 marks · −1

Which of the following nuclear fragments corresponding to nuclear fission between neutron (01n)\left({}^1_0n\right) and uranium isotope (92235U)\left({}^{235}_{92}U\right) is correct:

  1. A.56144Ba+3689Kr+4 01n{}^{144}_{56}\text{Ba}+{}^{89}_{36}\text{Kr}+4\,{}^1_0n
  2. B.56144Ba+3689Kr+3 01n{}^{144}_{56}\text{Ba}+{}^{89}_{36}\text{Kr}+3\,{}^1_0n
  3. C.56140Xe+3894Sr+3 01n{}^{140}_{56}\text{Xe}+{}^{94}_{38}\text{Sr}+3\,{}^1_0n
  4. D.51153Sb+4199Nb+3 01n{}^{153}_{51}\text{Sb}+{}^{99}_{41}\text{Nb}+3\,{}^1_0n

Correct answer: B

Explanation: Mass number 236 and charge 92 must balance.

Question 19

Physics · 4 marks · −1

The value of net resistance of the network as shown in the given figure is:

Figure for question 19
  1. A.6Ω
  2. B.(5/2)Ω
  3. C.(15/4)Ω
  4. D.(30/11)Ω

Correct answer: A

Explanation: The 5 Ω branch is blocked; 15∥10=6 Ω15\parallel10=6\ \Omega.

Question 20

Physics · 4 marks · −1

Two forces F⃗1\vec F_1 and F⃗2\vec F_2 are acting on a body. One force has magnitude thrice that of the other force and the resultant of the two forces is equal to the force of larger magnitude. The angle between F⃗1\vec F_1 and F⃗2\vec F_2 is cos⁡−1(1n)\cos^{-1}\left(\frac1n\right). The value of ∣n∣|n| is ______.

Correct answer: 6

Explanation: 9=1+9+6cos⁡θ⇒cos⁡θ=−169=1+9+6\cos\theta\Rightarrow\cos\theta=-\frac16.

Question 21

Physics · 4 marks · −1

A solid sphere and a hollow cylinder roll up without slipping on same inclined plane with same initial speed vv. The sphere and the cylinder reaches upto maximum heights h1h_1 and h2h_2, respectively, above the initial level. The ratio h1:h2h_1:h_2 is n10\frac{n}{10}. The value of nn is ______.

Correct answer: 7

Explanation: h1=7v210gh_1=\frac{7v^2}{10g}, h2=v2gh_2=\frac{v^2}{g}.

Question 22

Physics · 4 marks · −1

An elastic spring under tension of 3 N has a length aa. Its length is bb under tension 2 N. For its length (3a−2b)(3a-2b), the value of tension will be ______ N.

Correct answer: 5

Explanation: T=k(l−l0)T=k(l-l_0): k(3a−2b−l0)=3(3)−2(2)=5k(3a-2b-l_0)=3(3)-2(2)=5 N.

Question 23

Physics · 4 marks · −1

A soap bubble is blown to a diameter of 7 cm. 36960 erg of work is done in blowing it further. If surface tension of soap solution is 40 dyne/cm then the new radius is ______ cm. Take (π=227)\left(\pi=\frac{22}{7}\right)

Correct answer: 7

Explanation: W=2T⋅4π(r2−3.52)⇒r2=49W=2T\cdot4\pi(r^2-3.5^2)\Rightarrow r^2=49.

Question 24

Physics · 4 marks · −1

An infinite plane sheet of charge having uniform surface charge density +σs+\sigma_s C/m² is placed on x−yx-y plane. Another infinitely long line charge having uniform linear charge density +λe+\lambda_e C/m is placed at z=4z=4 m plane and parallel to y-axis. If the magnitude values ∣σs∣=2∣λe∣|\sigma_s|=2|\lambda_e| then at point (0, 0, 2), the ratio of magnitudes of electric field values due to sheet charge to that of line charge is πn:1\pi\sqrt n:1. The value of nn is ______.

Correct answer: 16

Explanation: σ/2ϵ0λ/(2πϵ0⋅2)=2πσλ=4π\frac{\sigma/2\epsilon_0}{\lambda/(2\pi\epsilon_0\cdot2)}=\frac{2\pi\sigma}{\lambda}=4\pi.

Question 25

Physics · 4 marks · −1

Twelve wires each having resistance 2Ω are joined to form a cube. A battery of 6 V emf is joined across point a and c. The voltage difference between e and f is ______ V.

Figure for question 25

Correct answer: 1

Question 26

Physics · 4 marks · −1

The magnetic field existing in a region is given by B⃗=0.2(1+2x)k^\vec B=0.2(1+2x)\hat k T. A square loop of edge 50 cm carrying 0.5 A current is placed in x−yx-y plane with its edges parallel to the x−yx-y axes, as shown in figure. The magnitude of the net magnetic force experienced by the loop is ______ mN.

Figure for question 26

Correct answer: 50

Explanation: Forces on the two edges parallel to y differ: F=IL ΔB=0.5×0.5×(0.2×2×0.5)=0.05F=IL\,\Delta B=0.5\times0.5\times(0.2\times2\times0.5)=0.05 N.

Question 27

Physics · 4 marks · −1

A alternating current at any instant is given by i=[6+56sin⁡(100πt+π/3)]i=[6+\sqrt{56}\sin(100\pi t+\pi/3)] A. The rms value of the current is ______ A.

Correct answer: 8

Explanation: 36+28=8\sqrt{36+28}=8.

Question 28

Physics · 4 marks · −1

Two wavelengths λ1\lambda_1 and λ2\lambda_2 are used in Young's double slit experiment. λ1=450\lambda_1=450 nm and λ2=650\lambda_2=650 nm. The minimum order of fringe produced by λ2\lambda_2 which overlaps with the fringe produced by λ1\lambda_1 is nn. The value of nn is ______.

Correct answer: 9

Explanation: 450n1=650n2450n_1=650n_2: n2=9n_2=9.

Question 29

Physics · 4 marks · −1

A hydrogen atom changes its state from n=3n=3 to n=2n=2. Due to recoil, the percentage change in the wave length of emitted light is approximately 1×10−n1\times10^{-n}. The value of nn is ______. [Given Rhc = 13.6 eV, hc = 1242 eV nm, h = 6.6×10−346.6\times10^{-34} J s mass of the hydrogen atom = 1.6×10−271.6\times10^{-27} kg]

Correct answer: 7

Explanation: Δλλ≈E2Mc2=1.892×9×108≈10−9\frac{\Delta\lambda}{\lambda}\approx\frac{E}{2Mc^2}=\frac{1.89}{2\times9\times10^8}\approx10^{-9}, i.e. 10−7%10^{-7}\%.

Question 30

Chemistry · 4 marks · −1

Number of elements from the following that CANNOT form compounds with valencies which match with their respective group valencies is ______. B, C, N, S, O, F, P, Al, Si

  1. A.7
  2. B.3
  3. C.5
  4. D.6

Correct answer: B

Explanation: N (max covalency 4), O and F cannot show their group valency.

Question 31

Chemistry · 4 marks · −1

The correct order of first ionization enthalpy values of the following elements is: (A) O (B) N (C) Be (D) F (E) B. Choose the correct answer from the options given below:

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

Correct answer: A

Explanation: B (801) < Be (899) < O (1314) < N (1402) < F (1681) kJ/mol.

Question 32

Chemistry · 4 marks · −1

Which one of the following molecules has maximum dipole moment?

  1. A.NF3\text{NF}_3
  2. B.CH4\text{CH}_4
  3. C.PF5\text{PF}_5
  4. D.NH3\text{NH}_3

Correct answer: D

Question 33

Chemistry · 4 marks · −1

Number of molecules/ions from the following in which the central atom is involved in sp3sp^3 hybridization is: NO3−\text{NO}_3^-, BCl3\text{BCl}_3, ClO2−\text{ClO}_2^-, ClO3\text{ClO}_3

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

Correct answer: C

Explanation: ClO2−_2^- and ClO3_3 (ClO3−_3^-).

Question 34

Chemistry · 4 marks · −1

Match List I with List II: List-I (Mechanism steps): (A) resonance in aniline (lone pair on N delocalised into the ring); (B) cyclohexene + H+^+ → secondary carbocation (π electrons move towards H+^+); (C) cyclohexene + −^-CN → carbanion (π electrons move away from the attacking nucleophile); (D) resonance in nitrobenzene (ring π electrons delocalised onto the NO2_2 group) List-II (Effect): (I) −E effect; (II) −R effect; (III) +E effect; (IV) +R effect Choose the correct answer from the options given below:

Figure for question 34
  1. A.(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
  2. B.(A)-(I), (B)-(II), (C)-(IV), (D)-(III)
  3. C.(A)-(III), (B)-(I), (C)-(II), (D)-(IV)
  4. D.(A)-(II), (B)-(IV), (C)-(III), (D)-(I)

Correct answer: A

Question 35

Chemistry · 4 marks · −1

Which of the following nitrogen containing compound does not give Lassaigne's test?

  1. A.Urea
  2. B.Phenyl hydrazine
  3. C.Glycene
  4. D.Hydrazine

Correct answer: D

Explanation: Hydrazine has no carbon, so no NaCN forms on fusion.

Question 36

Chemistry · 4 marks · −1

Which among the following is incorrect statement?

  1. A.Electromeric effect dominates over inductive effect
  2. B.The electromeric effect is, temporary effect
  3. C.Hydrogen ion (H+^+) shows negative electromeric effect
  4. D.The organic compound shows electromeric effect in the presence of the reagent only.

Correct answer: C

Explanation: Attack by an electrophile such as H+^+ produces a +E effect.

Question 37

Chemistry · 4 marks · −1

(A) 1-bromo-4-(2-bromoethyl)benzene (pp-Br-C6H4-CH2CH2Br\text{Br-C}_6\text{H}_4\text{-CH}_2\text{CH}_2\text{Br}) →NaOH(alc)\xrightarrow{\text{NaOH(alc)}} (B) →HBr, Ether\xrightarrow{\text{HBr, Ether}} (C). Identify (B) and (C) and how are (A) and (C) related?

Figure for question 37
  1. A.B = 4-(2-bromoethyl)phenol, C = 4-(2-hydroxyethyl)phenol; functional group isomers
  2. B.B = 4-bromostyrene, C = 1-bromo-4-(2-bromoethyl)benzene; chain isomers
  3. C.B = 4-bromostyrene, C = 1-bromo-4-(1-bromoethyl)benzene; position isomers
  4. D.B = 4-(2-bromoethyl)phenol, C = 4-(1-bromoethyl)phenol; derivative

Correct answer: C

Explanation: Dehydrohalogenation gives 4-bromostyrene; Markovnikov addition of HBr gives the benzylic bromide, a position isomer of A.

Question 38

Chemistry · 4 marks · −1

The Molarity (M) of an aqueous solution containing 5.85 g of NaCl in 500 mL water is: (Given : Molar Mass Na : 23 and Cl : 35.5 g mol−1^{-1})

  1. A.2
  2. B.20
  3. C.4
  4. D.0.2

Correct answer: D

Question 39

Chemistry · 4 marks · −1

What pressure (bar) of H2\text{H}_2 would be required to make emf of hydrogen electrode zero in pure water at 25°C?

  1. A.10−710^{-7}
  2. B.0.5
  3. C.1
  4. D.10−1410^{-14}

Correct answer: D

Explanation: E=−0.0592log⁡PH2[H+]2=0⇒P=10−14E=-\frac{0.059}{2}\log\frac{P_{\text{H}_2}}{[\text{H}^+]^2}=0\Rightarrow P=10^{-14} bar.

Question 40

Chemistry · 4 marks · −1

One of the commonly used electrode is calomel electrode. Under which of the following categories, calomel electrode comes?

  1. A.Oxidation - Reduction electrodes
  2. B.Metal ion - Metal electrodes
  3. C.Gas - Ion electrodes
  4. D.Metal - Insoluble Salt - Anion electrodes

Correct answer: D

Question 41

Chemistry · 4 marks · −1

What will be the decreasing order of basic strength of the following conjugate bases? −^-OH, RO‾\overline{\text{O}}, CH3_3COO‾\overline{\text{O}}, Cl‾\overline{\text{l}}

  1. A.RO‾\overline{\text{O}} > −^-OH > CH3_3COO‾\overline{\text{O}} > Cl‾\overline{\text{l}}
  2. B.Cl‾\overline{\text{l}} > RO‾\overline{\text{O}} > −^-OH > CH3_3COO‾\overline{\text{O}}
  3. C.−^-OH > RO‾\overline{\text{O}} > CH3_3COO‾\overline{\text{O}} > Cl‾\overline{\text{l}}
  4. D.Cl‾\overline{\text{l}} > −^-OH > RO‾\overline{\text{O}} > CH3_3COO‾\overline{\text{O}}

Correct answer: A

Question 42

Chemistry · 4 marks · −1

The element which shows only one oxidation state other than its elemental form is:

  1. A.Cobalt
  2. B.Titanium
  3. C.Nickel
  4. D.Scandium

Correct answer: D

Question 43

Chemistry · 4 marks · −1

Number of complexes from the following with even number of unpaired "d" electrons is [V(H2O)6]3+[\text{V(H}_2\text{O)}_6]^{3+}, [Cr(H2O)6]2+[\text{Cr(H}_2\text{O)}_6]^{2+}, [Fe(H2O)6]3+[\text{Fe(H}_2\text{O)}_6]^{3+}, [Ni(H2O)6]3+[\text{Ni(H}_2\text{O)}_6]^{3+}, [Cu(H2O)6]2+[\text{Cu(H}_2\text{O)}_6]^{2+} [Given atomic numbers : V = 23, Cr = 24, Fe = 26, Ni = 28 Cu = 29]

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

Correct answer: A

Explanation: V3+^{3+} (2) and Cr2+^{2+} (4) are even; Fe3+^{3+} (5), Ni3+^{3+} (3), Cu2+^{2+} (1) are odd.

Question 44

Chemistry · 4 marks · −1

The correct sequence of ligands in the order of decreasing field strength is:

  1. A.NCS−^- > EDTA4−^{4-} > CN−^- > CO
  2. B.CO > H2_2O > F−^- > S2−^{2-}
  3. C.S2−^{2-} > −^-OH > EDTA4−^{4-} > CO
  4. D.−^-OH > F−^- > NH3_3 > CN−^-

Correct answer: B

Question 45

Chemistry · 4 marks · −1

Identify the correct set of reagents or reaction conditions 'X' and 'Y' in the following set of transformation: CH3-CH2-CH2-Br→′X′\text{CH}_3\text{-CH}_2\text{-CH}_2\text{-Br}\xrightarrow{'X'} Product →′Y′CH3-CH(Br)-CH3\xrightarrow{'Y'}\text{CH}_3\text{-CH(Br)-CH}_3

  1. A.X = dil.aq. NaOH, 20°C, Y = Br2_2/CHCl3_3
  2. B.X = conc.alc. NaOH, 80°C, Y = Br2_2/CHCl3_3
  3. C.X = dil.aq. NaOH, 20°C, Y = HBr/acetic acid
  4. D.X = conc.alc. NaOH, 80°C, Y = HBr/acetic acid

Correct answer: D

Question 46

Chemistry · 4 marks · −1

Given below are two statements: Statements I : Acidity of α-hydrogens of aldehydes and ketones is responsible for Aldol reaction. Statement II : Reaction between benzaldehyde and ethanal will NOT give Cross - Aldol product. 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 correct
  3. C.Both Statement I and Statement II are incorrect
  4. D.Statement I is incorrect but Statement II is correct

Correct answer: A

Question 47

Chemistry · 4 marks · −1

In the precipitation of the iron group (III) in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide to:

  1. A.increase concentration of Cl−^- ions
  2. B.increase concentration of NH4+_4^+ ions
  3. C.prevent interference by phosphate ions
  4. D.decrease concentration of −^-OH ions

Correct answer: D

Question 48

Chemistry · 4 marks · −1

Which of the following is the correct structure of L-Glucose?

Figure for question 48
  1. A.Fischer projection (C2→C5): HO left, OH right, HO left, HO left
  2. B.OH right, HO left, OH right, OH right... as drawn (D-glucose-like pattern)
  3. C.HO left on all four stereocentres
  4. D.HO, HO left; OH, OH right

Correct answer: A

Explanation: L-glucose is the mirror image of D-glucose (D: right, left, right, right at C2–C5).

Question 49

Chemistry · 4 marks · −1

The de-Broglie's wavelength of an electron in the 4th4^{th} orbit is ______ πa0\pi a_0. (a0a_0 = Bohr's radius)

Correct answer: 8

Explanation: 2πr4=4λ⇒λ=2π(16a0)4=8πa02\pi r_4=4\lambda\Rightarrow\lambda=\frac{2\pi(16a_0)}{4}=8\pi a_0.

Question 50

Chemistry · 4 marks · −1

Number of molecules/species from the following having one unpaired electron is ______. O2\text{O}_2, O2−1\text{O}_2^{-1}, NO, CN−1^{-1}, O22−\text{O}_2^{2-}

Correct answer: 2

Explanation: O2−_2^- and NO.

Question 51

Chemistry · 4 marks · −1

The enthalpy of formation of ethane (C2H6\text{C}_2\text{H}_6) from ethylene by addition of hydrogen where the bond-energies of C–H, C–C, C=C, H–H are 414 kJ, 347 kJ, 615 kJ and 435 kJ respectively is ______ kJ.

Correct answer: 125

Explanation: ΔH=(615+435)−(347+2×414)=−125\Delta H=(615+435)-(347+2\times414)=-125 kJ.

Question 52

Chemistry · 4 marks · −1

Only 2 mL of KMnO4\text{KMnO}_4 solution of unknown molarity is required to reach the end point of a titration of 20 mL of oxalic acid (2M) in acidic medium. The molarity of KMnO4\text{KMnO}_4 solution should be ______ M.

Correct answer: 8

Explanation: 2×M×5=20×2×2⇒M=82\times M\times5=20\times2\times2\Rightarrow M=8.

Question 53

Chemistry · 4 marks · −1

The number of different chain isomers for C7H16\text{C}_7\text{H}_{16} is ______.

Correct answer: 9

Question 54

Chemistry · 4 marks · −1

2.5 g of a non-volatile, non-electrolyte is dissolved in 100 g of water at 25°C. The solution showed a boiling point elevation by 2°C. Assuming the solute concentration is negligible with respect to the solvent concentration, the vapor pressure of the resulting aqueous solution is ______ mm of Hg (nearest integer) [Given : Molal boiling point elevation constant of water (Kb)=0.52(K_b)=0.52 K kg mol−1^{-1}, 1 atm pressure = 760 mm of Hg, molar mass of water = 18 g mol−1^{-1}]

Correct answer: 707

Explanation: m=20.52m=\frac{2}{0.52}; x2≈m×181000=0.0692x_2\approx\frac{m\times18}{1000}=0.0692; P=760(1−0.0692)≈707P=760(1-0.0692)\approx707 mm Hg.

Question 55

Chemistry · 4 marks · −1

Consider the following transformation involving first order elementary reaction in each step at constant temperature as shown below. A+B⇌Step 1Step 3C→Step 2PA+B\underset{\text{Step 3}}{\overset{\text{Step 1}}{\rightleftharpoons}}C\xrightarrow{\text{Step 2}}P. Some details of the above reactions are listed below. | Step | Rate constant (s−1^{-1}) | Activation energy (kJ mol−1^{-1}) | | 1 | k1k_1 | 300 | | 2 | k2k_2 | 200 | | 3 | k3k_3 | Ea3E_{a3} | If the overall rate constant of the above transformation (k) is given as k=k1k2k3k=\frac{k_1k_2}{k_3} and the overall activation energy (Ea)(E_a) is 400 kJ mol−1^{-1}, then the value of Ea3E_{a3} is ______ kJ mol−1^{-1} (nearest integer)

Correct answer: 100

Explanation: 400=300+200−Ea3400=300+200-E_{a3}.

Question 56

Chemistry · 4 marks · −1

Consider the following reaction MnO2+KOH+O2→A+H2O\text{MnO}_2+\text{KOH}+\text{O}_2\to A+\text{H}_2\text{O}. Product 'A' in neutral or acidic medium disproportionate to give products 'B' and 'C' along with water. The sum of spin-only magnetic moment values of B and C is ______ BM. (nearest integer) (Given atomic number of Mn is 25)

Correct answer: 4

Explanation: A = K2_2MnO4_4 → MnO4−_4^- (d0^0, 0 BM) + MnO2_2 (d3^3, 3.87 BM).

Question 57

Chemistry · 4 marks · −1

The number of the correct reaction(s) among the following is ______. (A) Benzene + benzoyl chloride →Anhyd. AlCl3\xrightarrow{\text{Anhyd. AlCl}_3} diphenylmethane (B) Benzoyl chloride →H2, Pd-BaSO4\xrightarrow{\text{H}_2,\ \text{Pd-BaSO}_4} benzoic acid (C) Benzene →CO, HCl, Anhyd. AlCl3/CuCl\xrightarrow{\text{CO, HCl, Anhyd. AlCl}_3/\text{CuCl}} benzaldehyde (D) Benzamide →H3O+, Δ\xrightarrow{\text{H}_3\text{O}^+,\ \Delta} aniline

Figure for question 57

Correct answer: 1

Explanation: Only the Gattermann–Koch reaction (C) is correct.

Question 58

Chemistry · 4 marks · −1

X g of ethylamine is subjected to reaction with NaNO2_2/HCl followed by water; evolved dinitrogen gas which occupied 2.24 L volume at STP. X is ______ ×10−1\times10^{-1} g.

Correct answer: 45

Explanation: 0.1 mol N2_2 ⇒ 0.1 mol C2_2H5_5NH2_2 = 4.5 g.

Question 59

Mathematics · 4 marks · −1

If 2 and 6 are the roots of the equation ax2+bx+1=0ax^2+bx+1=0, then the quadratic equation, whose roots are 12a+b\frac{1}{2a+b} and 16a+b\frac{1}{6a+b}, is:

  1. A.2x2+11x+12=02x^2+11x+12=0
  2. B.x2+8x+12=0x^2+8x+12=0
  3. C.4x2+14x+12=04x^2+14x+12=0
  4. D.x2+10x+16=0x^2+10x+16=0

Correct answer: B

Explanation: a=112a=\frac1{12}, b=−23b=-\frac23; roots −2 and −6.

Question 60

Mathematics · 4 marks · −1

Let α and β be the sum and the product of all the non-zero solutions of the equation (zˉ)2+∣z∣=0(\bar z)^2+|z|=0, z∈Cz\in\mathbb{C}. Then 4(α2+β2)4(\alpha^2+\beta^2) is equal to:

  1. A.6
  2. B.8
  3. C.2
  4. D.4

Correct answer: D

Explanation: Non-zero solutions are z=±iz=\pm i: α=0\alpha=0, β=1\beta=1.

Question 61

Mathematics · 4 marks · −1

There are 5 points P1,P2,P3,P4,P5P_1,P_2,P_3,P_4,P_5 on the side AB, excluding A and B, of a triangle ABC. Similarly there are 6 points P6,P7,…,P11P_6,P_7,\ldots,P_{11} on the side BC and 7 points P12,P13,…,P18P_{12},P_{13},\ldots,P_{18} on the side CA of the triangle. The number of triangles, that can be formed using the points P1,P2,…,P18P_1,P_2,\ldots,P_{18} as vertices, is:

  1. A.776
  2. B.796
  3. C.751
  4. D.771

Correct answer: C

Explanation: 18C3−5C3−6C3−7C3=816−65^{18}C_3-{}^5C_3-{}^6C_3-{}^7C_3=816-65.

Question 62

Mathematics · 4 marks · −1

Let the first three terms 2, p and q, with q≠2q\ne2, of a G.P. be respectively the 7th7^{th}, 8th8^{th} and 13th13^{th} terms of an A.P. If the 5th5^{th} term of the G.P. is the nthn^{th} term of the A.P., then n is equal to:

  1. A.163
  2. B.151
  3. C.177
  4. D.169

Correct answer: A

Explanation: (2+d)2=2(2+6d)⇒d=8(2+d)^2=2(2+6d)\Rightarrow d=8, ratio 5; 2⋅54=1250=−46+8(n−1)⇒n=1632\cdot5^4=1250=-46+8(n-1)\Rightarrow n=163.

Question 63

Mathematics · 4 marks · −1

The sum of all rational terms in the expansion of (215+513)15\left(2^{\frac15}+5^{\frac13}\right)^{15} is equal to:

  1. A.3133
  2. B.931
  3. C.6131
  4. D.633

Correct answer: A

Explanation: Only the first and last terms are rational: 8+31258+3125.

Question 64

Mathematics · 4 marks · −1

The vertices of a triangle are A(−1, 3), B(−2, 2) and C(3, −1). A new triangle is formed by shifting the sides of the triangle by one unit inwards. Then the equation of the side of the new triangle nearest to origin is:

  1. A.x+y+(2−2)=0x+y+(2-\sqrt2)=0
  2. B.−x+y−(2−2)=0-x+y-(2-\sqrt2)=0
  3. C.x+y−(2−2)=0x+y-(2-\sqrt2)=0
  4. D.x−y−(2+2)=0x-y-(2+\sqrt2)=0

Correct answer: C

Explanation: Side AC: x+y=2x+y=2 is nearest the origin; shifting it one unit towards the interior gives x+y=2−2x+y=2-\sqrt2.

Question 65

Mathematics · 4 marks · −1

A square is inscribed in the circle x2+y2−10x−6y+30=0x^2+y^2-10x-6y+30=0. One side of this square is parallel to y=x+3y=x+3. If (xi,yi)(x_i,y_i) are the vertices of the square, then Σ(xi2+yi2)\Sigma(x_i^2+y_i^2) is equal to:

  1. A.148
  2. B.152
  3. C.160
  4. D.156

Correct answer: B

Explanation: Centre (5, 3), radius 2; vertices (7,3),(3,3),(5,5),(5,1)(7,3),(3,3),(5,5),(5,1).

Question 66

Mathematics · 4 marks · −1

Let α,β∈R\alpha,\beta\in\mathbb{R}. Let the mean and the variance of 6 observations −3, 4, 7, −6, α, β be 2 and 23, respectively. The mean deviation about the mean of these 6 observations is:

  1. A.133\frac{13}{3}
  2. B.163\frac{16}{3}
  3. C.113\frac{11}{3}
  4. D.143\frac{14}{3}

Correct answer: A

Explanation: α+β=10\alpha+\beta=10, α2+β2=52\alpha^2+\beta^2=52: {6, 4}; deviations 5, 2, 5, 8, 4, 2.

Question 67

Mathematics · 4 marks · −1

Let α∈(0,∞)\alpha\in(0,\infty) and A=[12α101012]A=\begin{bmatrix}1&2&\alpha\\1&0&1\\0&1&2\end{bmatrix}. If det⁡(adj(2A−AT)⋅adj(A−2AT))=28\det\left(\text{adj}(2A-A^T)\cdot\text{adj}(A-2A^T)\right)=2^8, then (det⁡(A))2(\det(A))^2 is equal to:

  1. A.36
  2. B.16
  3. C.1
  4. D.49

Correct answer: B

Explanation: A−2AT=−(2A−AT)TA-2A^T=-(2A-A^T)^T, so the product of determinants is ∣2A−AT∣4=28|2A-A^T|^4=2^8; ∣2A−AT∣=−1−3α=±4⇒α=1|2A-A^T|=-1-3\alpha=\pm4\Rightarrow\alpha=1; ∣A∣=α−5=−4|A|=\alpha-5=-4.

Question 68

Mathematics · 4 marks · −1

If the system of equations x+(2sin⁡α)y+(2cos⁡α)z=0x+(\sqrt2\sin\alpha)y+(\sqrt2\cos\alpha)z=0, x+(cos⁡α)y+(sin⁡α)z=0x+(\cos\alpha)y+(\sin\alpha)z=0, x+(sin⁡α)y−(cos⁡α)z=0x+(\sin\alpha)y-(\cos\alpha)z=0 has a non-trivial solution, then α∈(0,π2)\alpha\in\left(0,\frac\pi2\right) is equal to:

  1. A.11π24\frac{11\pi}{24}
  2. B.5π24\frac{5\pi}{24}
  3. C.7π24\frac{7\pi}{24}
  4. D.3π4\frac{3\pi}{4}

Correct answer: B

Explanation: Δ=−1+2(sin⁡2α−cos⁡2α)=0⇒sin⁡(2α−π4)=12\Delta=-1+\sqrt2(\sin2\alpha-\cos2\alpha)=0\Rightarrow\sin(2\alpha-\frac\pi4)=\frac12.

Question 69

Mathematics · 4 marks · −1

If the domain of the function sin⁡−1(3x−222x−19)+log⁡e(3x2−8x+5x2−3x−10)\sin^{-1}\left(\frac{3x-22}{2x-19}\right)+\log_e\left(\frac{3x^2-8x+5}{x^2-3x-10}\right) is (α,β](\alpha,\beta], then 3α+10β3\alpha+10\beta is equal to:

  1. A.100
  2. B.95
  3. C.97
  4. D.98

Correct answer: C

Explanation: The sin⁡−1\sin^{-1} condition gives 3≤x≤4153\le x\le\frac{41}{5}; the log condition keeps x>5x>5 there: domain (5,415](5,\frac{41}{5}], 15+82=9715+82=97.

Question 70

Mathematics · 4 marks · −1

Let the sum of the maximum and the minimum values of the function f(x)=2x2−3x+82x2+3x+8f(x)=\frac{2x^2-3x+8}{2x^2+3x+8} be mn\frac mn, where gcd(m, n) = 1. Then m + n is equal to:

  1. A.195
  2. B.201
  3. C.217
  4. D.182

Correct answer: B

Explanation: Range endpoints satisfy 9(y+1)2=64(y−1)29(y+1)^2=64(y-1)^2: y=115,511y=\frac{11}{5},\frac5{11}; sum 14655\frac{146}{55}.

Question 71

Mathematics · 4 marks · −1

Let f:R→Rf:\mathbb{R}\to\mathbb{R} be a function given by f(x)={1−cos⁡2xx2,x<0α,x=0β1−cos⁡xx,x>0f(x)=\begin{cases}\frac{1-\cos2x}{x^2}, & x<0\\ \alpha, & x=0\\ \frac{\beta\sqrt{1-\cos x}}{x}, & x>0\end{cases}, where α,β∈R\alpha,\beta\in\mathbb{R}. If f is continuous at x = 0, then α2+β2\alpha^2+\beta^2 is equal to:

  1. A.3
  2. B.12
  3. C.48
  4. D.6

Correct answer: B

Explanation: α=2\alpha=2, β2=2\frac{\beta}{\sqrt2}=2.

Question 72

Mathematics · 4 marks · −1

Let f(x)=x5+2ex/4f(x)=x^5+2e^{x/4} for all x∈Rx\in\mathbb{R}. Consider a function g(x) such that (g∘f)(x)=x(g\circ f)(x)=x for all x∈Rx\in\mathbb{R}. Then the value of 8g′(2)8g'(2) is:

  1. A.2
  2. B.8
  3. C.4
  4. D.16

Correct answer: D

Explanation: f(0)=2f(0)=2, f′(0)=12f'(0)=\frac12, so g′(2)=2g'(2)=2.

Question 73

Mathematics · 4 marks · −1

Let f(x)={−2,−2≤x≤0x−2,0<x≤2f(x)=\begin{cases}-2, & -2\le x\le0\\ x-2, & 0<x\le2\end{cases} and h(x)=f(∣x∣)+∣f(x)∣h(x)=f(|x|)+|f(x)|. Then ∫−22h(x)dx\int_{-2}^{2}h(x)dx is equal to:

  1. A.1
  2. B.6
  3. C.4
  4. D.2

Correct answer: D

Explanation: h=−xh=-x on [−2,0][-2,0] and 0 on (0,2](0,2].

Question 74

Mathematics · 4 marks · −1

If the solution y=y(x)y=y(x) of the differential equation (x4+2x3+3x2+2x+2)dy−(2x2+2x+3)dx=0(x^4+2x^3+3x^2+2x+2)dy-(2x^2+2x+3)dx=0 satisfies y(−1)=−π4y(-1)=-\frac\pi4, then y(0)y(0) is equal to:

  1. A.π2\frac\pi2
  2. B.−π2-\frac\pi2
  3. C.0
  4. D.π4\frac\pi4

Correct answer: D

Explanation: The denominator is (x2+1)(x2+2x+2)(x^2+1)(x^2+2x+2) and the integrand splits as 1x2+1+1(x+1)2+1\frac1{x^2+1}+\frac1{(x+1)^2+1}: y=tan⁡−1x+tan⁡−1(x+1)y=\tan^{-1}x+\tan^{-1}(x+1).

Question 75

Mathematics · 4 marks · −1

Let the point, on the line passing through the points P(1, −2, 3) and Q(5, −4, 7), farther from the origin and at distance of 9 units from the point P, be (α,β,γ)(\alpha,\beta,\gamma). Then α2+β2+γ2\alpha^2+\beta^2+\gamma^2 is equal to:

  1. A.165
  2. B.160
  3. C.155
  4. D.150

Correct answer: C

Explanation: Candidates P±(6,−3,6)P\pm(6,-3,6): (7, −5, 9) is farther.

Question 76

Mathematics · 4 marks · −1

Three urns A, B and C contain 7 red, 5 black; 5 red, 7 black and 6 red, 6 black balls, respectively. One of the urn is selected at random and a ball is drawn from it. If the ball drawn is black, then the probability that it is drawn from urn A is:

  1. A.518\frac5{18}
  2. B.516\frac5{16}
  3. C.417\frac4{17}
  4. D.718\frac7{18}

Correct answer: A

Explanation: 55+7+6\frac{5}{5+7+6}.

Question 77

Mathematics · 4 marks · −1

Let a=1+2C23!+3C24!+4C25!+…a=1+\frac{{}^2C_2}{3!}+\frac{{}^3C_2}{4!}+\frac{{}^4C_2}{5!}+\ldots, b=1+1C0+1C11!+2C0+2C1+2C22!+3C0+3C1+3C2+3C33!+…b=1+\frac{{}^1C_0+{}^1C_1}{1!}+\frac{{}^2C_0+{}^2C_1+{}^2C_2}{2!}+\frac{{}^3C_0+{}^3C_1+{}^3C_2+{}^3C_3}{3!}+\ldots. Then 2ba2\frac{2b}{a^2} is equal to ______.

Correct answer: 8

Explanation: nC2(n+1)!=12[1(n−1)!−2n!+2(n+1)!]\frac{{}^nC_2}{(n+1)!}=\frac12\left[\frac1{(n-1)!}-\frac2{n!}+\frac2{(n+1)!}\right] sums to e−22\frac{e-2}{2}, so a=e2a=\frac e2; b=∑2nn!=e2b=\sum\frac{2^n}{n!}=e^2; 2ba2=8\frac{2b}{a^2}=8.

Question 78

Mathematics · 4 marks · −1

Let the length of the focal chord PQ of the parabola y2=12xy^2=12x be 15 units. If the distance of PQ from the origin is p, then 10p210p^2 is equal to ______.

Correct answer: 72

Explanation: 12cosec⁡2θ=15⇒sin⁡2θ=4512\operatorname{cosec}^2\theta=15\Rightarrow\sin^2\theta=\frac45; p=3sin⁡θp=3\sin\theta.

Question 79

Mathematics · 4 marks · −1

If lim⁡x→1(5x+1)1/3−(x+5)1/3(2x+3)1/2−(x+4)1/2=m5n(2n)2/3\lim_{x\to1}\frac{(5x+1)^{1/3}-(x+5)^{1/3}}{(2x+3)^{1/2}-(x+4)^{1/2}}=\frac{m\sqrt5}{n(2n)^{2/3}}, where gcd(m, n) = 1, then 8m + 12n is equal to ______.

Correct answer: 100

Question 80

Mathematics · 4 marks · −1

In a survey of 220 students of a higher secondary school, it was found that at least 125 and at most 130 students studied Mathematics; at least 85 and at most 95 studied Physics; at least 75 and at most 90 studied Chemistry; 30 studied both Physics and Chemistry; 50 studied both Chemistry and Mathematics; 40 studied both Mathematics and Physics and 10 studied none of these subjects. Let m and n respectively be the least and the most number of students who studied all the three subjects. Then m + n is equal to ______.

Correct answer: 45

Question 81

Mathematics · 4 marks · −1

Let A be a 3×33\times3 matrix of non-negative real elements such that A[111]=3[111]A\begin{bmatrix}1\\1\\1\end{bmatrix}=3\begin{bmatrix}1\\1\\1\end{bmatrix}. Then the maximum value of det(A) is ______.

Correct answer: 27

Explanation: Each row sums to 3; the maximum determinant is attained by 3I3I: 27.

Question 82

Mathematics · 4 marks · −1

If ∫0π/4sin⁡2x1+sin⁡xcos⁡xdx=1alog⁡e(a3)+πb3\int_0^{\pi/4}\frac{\sin^2x}{1+\sin x\cos x}dx=\frac1a\log_e\left(\frac a3\right)+\frac{\pi}{b\sqrt3}, where a,b∈Na,b\in\mathbb{N}, then a + b is equal to ______.

Correct answer: 8

Question 83

Mathematics · 4 marks · −1

Let the solution y = y(x) of the differential equation dydx−y=1+4sin⁡x\frac{dy}{dx}-y=1+4\sin x satisfy y(π)=1y(\pi)=1. Then y(π2)+10y\left(\frac\pi2\right)+10 is equal to ______.

Correct answer: 7

Explanation: y=−1−2(sin⁡x+cos⁡x)+Cexy=-1-2(\sin x+\cos x)+Ce^x with C=0C=0; y(π2)=−3y(\frac\pi2)=-3.

Question 84

Mathematics · 4 marks · −1

Let ABC be a triangle of area 15215\sqrt2 and the vectors AB⃗=i^+2j^−7k^\vec{AB}=\hat i+2\hat j-7\hat k, BC⃗=ai^+bj^+ck^\vec{BC}=a\hat i+b\hat j+c\hat k and AC⃗=6i^+dj^−2k^\vec{AC}=6\hat i+d\hat j-2\hat k, d > 0. Then the square of the length of the largest side of the triangle ABC is ______.

Correct answer: 54

Question 85

Mathematics · 4 marks · −1

If the shortest distance between the lines x+22=y+33=z−54\frac{x+2}{2}=\frac{y+3}{3}=\frac{z-5}{4} and x−31=y−2−3=z+42\frac{x-3}{1}=\frac{y-2}{-3}=\frac{z+4}{2} is 3835k\frac{38}{3\sqrt5}k, and ∫0k[x2]dx=α−α\int_0^k[x^2]dx=\alpha-\sqrt\alpha, where [x] denotes the greatest integer function, then 6α36\alpha^3 is equal to ______.

Correct answer: 48

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