JEE Main 2025 — 3 Apr Shift 1 (Previous Year Paper)
JEE Main · 2025 · with answers and explanations
- questions
- 74
- Total marks
- 296
- Duration
- 180 minutes
- Negative marking
- −1
Subjects: Mathematics · Physics · Chemistry
Question 1
Mathematics · 4 marks · −1Let A be a matrix of order 3 x 3 and . If , , then is equal to
- A.26
- B.28
- C.27
- D.25
Correct answer: C
Explanation: , has det ; ; adj squares it: ; times : → 27.
Question 2
Mathematics · 4 marks · −1The sum of all rational terms in the expansion of is
- A.18817
- B.33845
- C.16923
- D.3763
Correct answer: A
Explanation: .
Question 3
Mathematics · 4 marks · −1The radius of the smallest circle which touches the parabolas and is
- A.
- B.
- C.
- D.
Correct answer: A
Explanation: The parabolas are mirror images in ; nearest points have slope 1: , point , distance to is .
Question 4
Mathematics · 4 marks · −1If , , then is equal to
- A.-1
- B.1
- C.27
- D.28
Correct answer: A
Explanation: ; y\'\'+y=-1.
Question 5
Mathematics · 4 marks · −1Let and be the roots of , and and be the roots of . If and , then is equal to
- A.7
- B.4
- C.5
- D.3
Correct answer: C
Explanation: → 8; → −3; total 5.
Question 6
Mathematics · 4 marks · −1Line passes through the point (1, 2, 3) and is parallel to z-axis. Line passes through the point (, 5, 6) and is parallel to y-axis. Let for , , the shortest distance between the two lines be 3. Then the square of the distance of the point (, , 7) from the line is
- A.32
- B.37
- C.25
- D.40
Correct answer: C
Explanation: SD : ; distance² of (4,−2,7) from : .
Question 7
Mathematics · 4 marks · −1Let be such that . Then the sum of all possible values of is
- A.-19 + 2i
- B.19 + 2i
- C.19 − 2i
- D.-19 − 2i
Correct answer: D
Explanation: : , ; .
Question 8
Mathematics · 4 marks · −1Let a line passing through the point (4, 1, 0) intersect the line at the point A() and the line at the point B(a, b, c). Then is equal to
- A.16
- B.8
- C.6
- D.12
Correct answer: B
Question 9
Mathematics · 4 marks · −1The sum 1 + 3 + 11 + 25 + 45 + 71 + ... upto 20 terms, is equal to
- A.8124
- B.7240
- C.6982
- D.7130
Correct answer: B
Explanation: Successive differences 2, 8, 14, … form an AP (d = 6), so and .
Question 10
Mathematics · 4 marks · −1Let be a G.P. of increasing positive numbers. If and , then is equal to
- A.128
- B.131
- C.130
- D.129
Correct answer: D
Explanation: , , , : .
Question 11
Mathematics · 4 marks · −1Let A = {−3, −2, −1, 0, 1, 2, 3}. Let R be a relation on A defined by xRy if and only if . Let be the number of elements in R and m be the minimum number of elements required to be added in R to make it a reflexive relation. Then is equal to
- A.17
- B.18
- C.19
- D.20
Correct answer: B
Question 12
Mathematics · 4 marks · −1Let the domain of the function be (a, b). If , , , where is the greatest integer function, then p + q + r is equal to
- A.9
- B.10
- C.8
- D.11
Correct answer: B
Question 13
Mathematics · 4 marks · −1A line passes through the origin and makes equal angles with the positive coordinate axes. It intersects the lines and , p > 0, at the points A and B, respectively. If and the foot of the perpendicular from the point A on the line is M, then is equal to
- A.3
- B.2
- C.4
- D.5
Correct answer: A
Question 14
Mathematics · 4 marks · −1A line passing through the point P(, ) intersects the ellipse at A and B such that (PA)·(PB) is maximum. Then is equal to :
- A.218
- B.377
- C.290
- D.338
Correct answer: D
Question 15
Mathematics · 4 marks · −1If the domain of the function is , then is equal to
- A.7
- B.4
- C.3
- D.5
Correct answer: B
Explanation: needs ; log needs or : domain ; .
Question 16
Mathematics · 4 marks · −1Let g be a differentiable function such that , and let satisfy the differential equation , . If , then is equal to
- A.
- B.
- C.
- D.
Correct answer: A
Explanation: ; so ; .
Question 17
Mathematics · 4 marks · −1The number of solutions of the equation , is:
- A.4
- B.6
- C.5
- D.3
Correct answer: C
Question 18
Mathematics · 4 marks · −1Let be continuous at x = 0. Then is equal to:
- A.36
- B.48
- C.64
- D.72
Correct answer: B
Explanation: c = 8 (so denominator → 0), right limit ; , b = 2; .
Question 19
Mathematics · 4 marks · −1Let . If , then is equal to
- A.
- B.
- C.
- D.
Correct answer: A
Question 20
Mathematics · 4 marks · −1If , , then is equal to
- A.18
- B.27
- C.81
- D.9
Correct answer: C
Explanation: , : total ; .
Question 21
Mathematics · 4 marks · −1The area of the region bounded by the curve , the x-axis and the lines and is equal to ______.
Correct answer: 12
Question 22
Mathematics · 4 marks · −1Let the product of the focal distances of the point P(4, ) on the hyperbola H: be 32. Let the length of the conjugate axis of H be p and the length of its latus rectum be q. Then is equal to ______.
Correct answer: 120
Question 23
Mathematics · 4 marks · −1Let , , and be a unit vector such that and . If is perpendicular to , then is equal to ______.
Correct answer: 5
Question 24
Mathematics · 4 marks · −1All five letter words are made using all the letters A, B, C, D, E and arranged as in an English dictionary with serial numbers. Let the word at serial number n be denoted by . Let the probability of choosing the word satisfy , n > 1. If , , then is equal to : ______
Correct answer: 183
Explanation: Rank of CDBEA = 24+24+6+6+2+1+1 = 64; , so , : 183.
Question 25
Mathematics · 4 marks · −1If the number of seven-digit numbers, such that the sum of their digits is even, is ; , then m + n is equal to ______.
Correct answer: 14
Explanation: Exactly half of the numbers: , so n = 5, m = 9: 14.
Question 26
Physics · 4 marks · −1Match the LIST-I with LIST-II. LIST-I: A. B. C. D. . LIST-II: I. Chemical reaction II. Fusion with +ve Q value III. Fission IV. Fusion with −ve Q value. Choose the correct answer from the options given below:
- A.A-II, B-I, C-IV, D-III
- B.A-II, B-I, C-III, D-IV
- C.A-III, B-I, C-II, D-IV
- D.A-III, B-I, C-IV, D-II
Correct answer: C
Question 27
Physics · 4 marks · −1The work function of a metal is 3 eV. The color of the visible light that is required to cause emission of photoelectrons is
- A.Yellow
- B.Green
- C.Red
- D.Blue
Correct answer: D
Explanation: nm: only blue/violet end qualifies.
Question 28
Physics · 4 marks · −1A force of 49 N acts tangentially at the highest point of a sphere (solid) of mass 20 kg, kept on a rough horizontal plane. If the sphere rolls without slipping, then the acceleration of the center of the sphere is

- A.3.5
- B.0.35
- C.2.5
- D.0.25
Correct answer: A
Explanation: .
Question 29
Physics · 4 marks · −1The radiation pressure exerted by a 450 W light source on a perfectly reflecting surface placed at 2m away from it, is
- A. Pascals
- B.0
- C. Pascals
- D. Pascals
Correct answer: C
Explanation: W/m; Pa.
Question 30
Physics · 4 marks · −1A person measures mass of 3 different particles as 435.42 g, 226.3 g and 0.125 g. According to the rules for arithmetic operations with significant figures, the addition of the masses of 3 particles will be.
- A.661.845 g
- B.662 g
- C.661.84 g
- D.661.8 g
Correct answer: D
Question 31
Physics · 4 marks · −1The angle of projection of a particle is measured from the vertical axis as and the maximum height reached by the particle is . Here as function of can be presented as

- A.Graph: increases (concave up) from 0 at to maximum at
- B.Graph: decreases (concave up) from a maximum at towards 0 at
- C.Graph: rises from 0 to a maximum and falls back to 0 at (arch)
- D.Graph: decreases from a maximum at to 0 at , concave down (cosine-squared shape)
Correct answer: D
Explanation: : maximum at 0, zero at 90°, flat-topped (concave down initially).
Question 32
Physics · 4 marks · −1A piston of mass M is hung from a massless spring whose restoring force law goes as , where k is the spring constant of appropriate dimension. The piston separates the vertical chamber into two parts, where the bottom part is filled with 'n' moles of an ideal gas. An external work is done on the gas isothermally (at a constant temperature T) with the help of a heating filament (with negligible volume) mounted in lower part of the chamber, so that the piston goes up from a height to , the total energy delivered by the filament is :(Assume spring to be in its natural length before heating)

- A.
- B.
- C.
- D.
Correct answer: A
Question 33
Physics · 4 marks · −1During the melting of a slab of ice at 273 K at atmospheric pressure:
- A.Internal energy of the ice-water system decreases.
- B.Positive work is done on the ice-water system by the atmosphere.
- C.Positive work is done by the ice-water system on the atmosphere.
- D.Internal energy of ice-water system remains unchanged.
Correct answer: B
Explanation: Ice contracts on melting, so the atmosphere does positive work on the system.
Question 34
Physics · 4 marks · −1Choose the correct logic circuit for the given truth table having inputs A and B. Truth table: A=0, B=0, Y=0; A=0, B=1, Y=0; A=1, B=0, Y=1; A=1, B=1, Y=1.

- A.Circuit 1: A and B feed an OR gate; the OR output and A (direct wire) feed an AND gate giving Y
- B.Circuit 2: A and B feed an OR gate; the OR output and NOT(A) feed an AND gate giving Y
- C.Circuit 3: A and B feed an OR gate; NOT(OR output) and A feed an AND gate giving Y
- D.Circuit 4: A and B feed an OR gate; the OR output and A feed an AND gate giving Y (A taken from above)
Correct answer: D
Explanation: Y = A: , realised by feeding A and (A + B) into AND with no inverter.
Question 35
Physics · 4 marks · −1Which of the following curves possibly represent one-dimensional motion of a particle? A. Phase vs time: a straight line with positive slope crossing the time axis. B. Velocity vs displacement: a circle centred at the origin. C. Velocity vs time: a circle centred at the origin. D. Total distance vs time: a non-decreasing curve starting at the origin. Choose the correct answer from the options given below:

- A.A and B only
- B.A, B and C only
- C.A, C and D only
- D.A, B and D only
Correct answer: D
Explanation: A (SHM phase), B (SHM v–x ellipse/circle) and D are possible; C would need two velocities at one instant.
Question 36
Physics · 4 marks · −1Consider a completely full cylindrical water tank of height 1.6 m and of cross-sectional area 0.5 . It has a small hole in its side at a height 90 cm from the bottom. Assume, the cross-sectional area of the hole to be negligibly small as compared to that of the water tank. If a load 50 kg is applied at the top surface of the water in the tank then the velocity of the water coming out at the instant when the hole is opened is: (g = 10 )
- A.2 m/s
- B.3 m/s
- C.5 m/s
- D.4 m/s
Correct answer: D
Explanation: Extra pressure 1000 Pa ≡ 0.1 m of water; head 0.7 + 0.1 = 0.8 m; m/s.
Question 37
Physics · 4 marks · −1Two blocks of masses m and M, (M > m), are placed on a frictionless table as shown in figure. A massless spring with spring constant k is attached with the lower block. If the system is slightly displaced and released, then ( = coefficient of friction between the two blocks) A. The time period of small oscillation of the two blocks is B. The acceleration of the blocks is (x = displacement of the blocks from the mean position) C. The magnitude of the frictional force on the upper block is D. The maximum amplitude of the upper block, if it does not slip, is E. Maximum frictional force can be . Choose the correct answer from the options given below:

- A.A, B, D Only
- B.C, D, E Only
- C.A, B, C Only
- D.B, C, D Only
Correct answer: A
Question 38
Physics · 4 marks · −1The electrostatic potential on the surface of uniformly charged spherical shell of radius R = 10 cm is 120 V. The potential at the centre of shell, at a distance r = 5 cm from centre, and at a distance r = 15 cm from the centre of the shell respectively, are:
- A.0V, 0V, 80V
- B.40V, 40V, 80V
- C.0V, 120V, 40V
- D.120V, 120V, 80V
Correct answer: D
Question 39
Physics · 4 marks · −1A particle is released from height S above the surface of the earth. At certain height its kinetic energy is three times its potential energy. The height from the surface of the earth and the speed of the particle at that instant are respectively.
- A.
- B.
- C.
- D.
Correct answer: D
Explanation: ; .
Question 40
Physics · 4 marks · −1Match the LIST-I with LIST-II. LIST-I: A. Gravitational constant B. Gravitational potential energy C. Gravitational potential D. Acceleration due to gravity. LIST-II: I. II. III. IV. . Choose the correct answer from the options given below:
- A.A-II, B-IV, C-III, D-I
- B.A-III, B-II, C-I, D-IV
- C.A-I, B-III, C-IV, D-II
- D.A-IV, B-III, C-II, D-I
Correct answer: D
Question 41
Physics · 4 marks · −1Consider following statements for refraction of light through prism, when angle of deviation is minimum. A. The refracted ray inside prism becomes parallel to the base. B. Larger angle prisms provide smaller angle of minimum deviation. C. Angle of incidence and angle of emergence becomes equal. D. There are always two sets of angle of incidence for which deviation will be same except at minimum deviation setting. E. Angle of refraction becomes double of prism angle. Choose the correct answer from the options given below:
- A.B, D and E Only
- B.A, C and D Only
- C.B, C and D Only
- D.A, B and E Only
Correct answer: B
Question 42
Physics · 4 marks · −1The radii of curvature for a thin convex lens are 10 cm and 15 cm respectively. The focal length of the lens is 12 cm. The refractive index of the lens material is
- A.1.2
- B.1.8
- C.1.4
- D.1.5
Correct answer: D
Explanation: .
Question 43
Physics · 4 marks · −1A gas is kept in a container having walls which are thermally non-conducting. Initially the gas has a volume of 800 and temperature 27°C. The change in temperature when the gas is adiabatically compressed to 200 is: (Take = 1.5 ; is the ratio of specific heats at constant pressure and at constant volume)
- A.327 K
- B.600 K
- C.300 K
- D.522 K
Correct answer: C
Explanation: K; change 300 K.
Question 44
Physics · 4 marks · −1A parallel plate capacitor is filled equally (half) with two dielectrics of dielectric constants and , as shown in figures. The distance between the plates is d and area of each plate is A. If capacitance in first configuration and second configuration are and respectively, then is :

- A.
- B.
- C.
- D.
Correct answer: D
Explanation: , ; ratio .
Question 45
Physics · 4 marks · −1A loop ABCDA, carrying current I = 12 A, is placed in a plane, consists of two semi-circular segments of radius m and m. The magnitude of the resultant magnetic field at center O is T. The value of k is ______. (Given Tm)

Correct answer: 1
Explanation: T.
Question 46
Physics · 4 marks · −1A 4.0 cm long straight wire carrying a current of 8A is placed perpendicular to a uniform magnetic field of strength 0.15 T. The magnetic force on the wire is ______ mN.
Correct answer: 48
Explanation: N = 48 mN.
Question 47
Physics · 4 marks · −1Three identical spheres of mass m, are placed at the vertices of an equilateral triangle of length a. When released, they interact only through gravitational force and collide after a time T = 4 seconds. If the sides of the triangle are increased to length 2a and also the masses of the spheres are made 2m, then they will collide after ______ seconds.
Correct answer: 8
Explanation: : factor → 8 s.
Question 48
Physics · 4 marks · −1In the figure shown below, a resistance of 150.4 is connected in series to an ammeter A of resistance 240 . A shunt resistance of 10 is connected in parallel with the ammeter. The reading of the ammeter is ______ mA.

Correct answer: 5
Explanation: , I = 0.125 A; ammeter share mA.
Question 49
Physics · 4 marks · −1Two coherent monochromatic light beams of intensities 4I and 9I are superimposed. The difference between the maximum and minimum intensities in the resulting interference pattern is xI. The value of x is ______.
Correct answer: 24
Explanation: .
Question 50
Chemistry · 4 marks · −1Which of the following properties will change when system containing solution 1 will become solution 2? Solution 1: 10 mol of solute x + 10 L of water. Solution 2: 1 L of solution 1 + 1 mol of solute x + 1 L of water.

- A.Molar heat capacity
- B.Concentration
- C.Gibbs free energy
- D.Density
Correct answer: C
Explanation: Both solutions have the same composition (1 mol per L of water), so intensive properties stay the same; the extensive Gibbs energy changes with the amount.
Question 51
Chemistry · 4 marks · −1Correct order of limiting molar conductivity for cations in water at 298 K is :
- A.
- B.
- C.
- D.
Correct answer: B
Explanation: (S cm mol): 349.6, 119, 106, 73.5, 50.1.
Question 52
Chemistry · 4 marks · −1The metal ions that have the calculated spin-only magnetic moment value of 4.9 B.M. are : A. B. C. D. E. . Choose the correct answer from the options given below:
- A.B and E Only
- B.A, D and E Only
- C.A, B and E Only
- D.A, C and E Only
Correct answer: C
Explanation: 4 unpaired electrons: (), (), ().
Question 53
Chemistry · 4 marks · −1In a reaction A + B C, initial concentrations of A and B are related as . The half lives of A and B are 10 min and 40 min, respectively. If they start to disappear at the same time, both following first order kinetics, after how much time will the concentration of both the reactants be same ?
- A.60 min
- B.40 min
- C.20 min
- D.80 min
Correct answer: B
Explanation: min.
Question 54
Chemistry · 4 marks · −1Given below are two statements: Statement I : The N - N single bond is weaker and longer than that of P - P single bond. Statement II : Compounds of group 15 elements in + 3 oxidation states readily undergo disproportionation reactions. In the light of the above statements, choose the correct answer from the options given below
- A.Both Statement I and Statement II are false
- B.Both Statement I and Statement II are true
- C.Statement I is true but Statement II is false
- D.Statement I is false but Statement II is true
Correct answer: A
Question 55
Chemistry · 4 marks · −1Given below are two statements: Statement I : A catalyst cannot alter the equilibrium constant () of the reaction, temperature remaining constant. Statement II : A homogenous catalyst can change the equilibrium composition of a system, temperature remaining constant. In the light of the above statements, choose the correct answer from the options given below
- A.Statement I is false but Statement II is true
- B.Both Statement I and Statement II are false
- C.Both Statement I and Statement II are true
- D.Statement I is true but Statement II is false
Correct answer: D
Question 56
Chemistry · 4 marks · −1Among g (each) of the following elements, which one will have the highest number of atoms? Element: Pb, Po, Pr and Pt
- A.Pb
- B.Pr
- C.Po
- D.Pt
Correct answer: B
Explanation: Lowest atomic mass gives most atoms: Pr (140.9).
Question 57
Chemistry · 4 marks · −1Number of molecules from below which cannot give iodoform reaction is: Ethanol, Isopropyl alcohol, Bromoacetone, 2−Butanol, 2−Butanone, Butanal, 2−Pentanone, 3−Pentanone, Pentanal and 3−Pentanol.
- A.5
- B.2
- C.4
- D.3
Correct answer: C
Explanation: Cannot: butanal, 3-pentanone, pentanal, 3-pentanol = 4.
Question 58
Chemistry · 4 marks · −1In the following system, at equilibrium, upon addition of xenon gas at constant T & p, the concentration of
- A., & remain constant
- B. will increase
- C. will decrease
- D. will increase
Correct answer: D
Explanation: Adding inert gas at constant p increases the volume, so the equilibrium shifts forward (more moles of PCl3 and Cl2).
Question 59
Chemistry · 4 marks · −1Which of the following statements are correct? A. The process of adding an electron to a neutral gaseous atom is always exothermic. B. The process of removing an electron from an isolated gaseous atom is always endothermic. C. The ionization energy of boron is less than that of beryllium. D. The electronegativity of C is 2.5 in and E. Li is the most electropositive among elements of group I. Choose the correct answer from the options given below:
- A.B and C Only
- B.B and D Only
- C.A, C and D Only
- D.B, C and E Only
Correct answer: A
Question 60
Chemistry · 4 marks · −1The correct order of the complexes (A), (B), (C) and (D) in terms of wavelength of light absorbed is
- A.C > B > D > A
- B.D > A > B > C
- C.C > B > A > D
- D.D > C > B > A
Correct answer: B
Explanation: Larger → shorter λ: : C > B > A > D, so λ: D > A > B > C.
Question 61
Chemistry · 4 marks · −1The least acidic compound, among the following is: (A) 3-ethoxyphenol (B) benzenesulfonic acid (C) butanoic acid () (D) ethyl propiolate ()

- A.C
- B.A
- C.B
- D.D
Correct answer: D
Explanation: The terminal alkyne C–H (pKa ≈ 20+) is far less acidic than a phenol, carboxylic or sulfonic acid.
Question 62
Chemistry · 4 marks · −1Which of the following is the correct structure of L−Fructose? (Fischer projections, top to bottom: C1 , C2 C=O, then C3, C4, C5, then C6 ; the side on which each OH is drawn is given.)

- A.C3 OH left, C4 OH left, C5 OH left
- B.C3 OH right, C4 OH right, C5 OH left
- C.C3 OH left, C4 OH right, C5 OH left
- D.C3 OH right, C4 OH left, C5 OH left
Correct answer: D
Explanation: D-fructose is C3 left, C4 right, C5 right; its mirror image L-fructose is C3 right, C4 left, C5 left.
Question 63
Chemistry · 4 marks · −1Which of the following postulate of Bohr's model of hydrogen atom is not in agreement with quantum mechanical model of an atom?
- A.An atom in a stationary state does not emit electromagnetic radiation as long as it stays in the same state.
- B.An atom can take only certain distinct energies , , , etc. These allowed states of constant energy are called the stationary states of atom.
- C.The electron in a H atom's stationary state moves in a circle around the nucleus.
- D.When an electron makes a transition from a higher energy stationary state to a lower energy stationary state, then it emits a photon of light.
Correct answer: C
Question 64
Chemistry · 4 marks · −1Match the LIST-I with LIST-II. LIST-I (Molecules/ion): A. B. C. D. . LIST-II (Hybridisation of central atom): I. II. III. IV. . Choose the correct answer from the options given below:
- A.A-IV, B-I, C-II, D-III
- B.A-II, B-III, C-IV, D-I
- C.A-I, B-II, C-III, D-IV
- D.A-III, B-I, C-IV, D-II
Correct answer: B
Question 65
Chemistry · 4 marks · −1Identify the correct statements from the following. A. Hexan-3-one and hexan-2-one (drawn as skeletal ketones) are metamers. B. Propyl cyanide () and propyl isocyanide () are functional isomers. C. Pentan-1-ol and 3-methylbutan-1-ol are position isomers. D. Pentan-1-amine and N-ethylpropan-1-amine (skeletal: ) are homologous. Choose the correct answer from the options given below:

- A.A & B Only
- B.B & C Only
- C.C & D Only
- D.A,B & C Only
Correct answer: A
Question 66
Chemistry · 4 marks · −1Which compound would give 3-methyl-6-oxoheptanal upon ozonolysis?

- A.1,3-Dimethylcyclohex-1-ene (second methyl on the ring carbon next to the =CH)
- B.1,4-Dimethylcyclohex-1-ene (second methyl two carbons away from the =CH)
- C.1,6-Dimethylcyclohex-1-ene (second methyl on the sp3 carbon next to the methyl-bearing alkene carbon)
- D.1,5-Dimethylcyclohex-1-ene (second methyl two carbons away from the methyl-bearing alkene carbon on the saturated side)
Correct answer: B
Explanation: 3-Methyl-6-oxoheptanal comes from cleaving the ring C=C of 1,4-dimethylcyclohexene.
Question 67
Chemistry · 4 marks · −1Identify [A], [B] and [C], respectively in the following reaction sequence: [A] benzenediazonium chloride [B] [C]

- A.[A] aniline, [B] iodobenzene, [C] biphenyl
- B.[A] aniline, [B] chlorobenzene, [C] iodobenzene
- C.[A] aniline, [B] chlorobenzene, [C] benzene
- D.[A] nitrobenzene, [B] iodobenzene, [C] biphenyl
Correct answer: A
Question 68
Chemistry · 4 marks · −12 moles each of ethylene glycol and glucose are dissolved in 500 g of water. The boiling point of the resulting solution is: (Given : Ebullioscopic constant of water = 0.52 K kg )
- A.375.3 K
- B.377.3 K
- C.379.2 K
- D.277.3 K
Correct answer: B
Explanation: K → 377.3 K.
Question 69
Chemistry · 4 marks · −1In the following reactions, which one is NOT correct?
- A.
- B.
- C.
- D.
Correct answer: A
Explanation: Ethanol reduces the diazonium salt to benzene (it is oxidised to ethanal); it does not give phenetole.
Question 70
Chemistry · 4 marks · −1During estimation of nitrogen by Dumas' method of compound X (0.42 g) [X = piperazine, a six-membered ring with two NH groups at positions 1 and 4] ______ mL of gas will be liberated at STP. (nearest integer) (Given molar mass in g : C : 12, H : 1, N : 14)

Correct answer: 109
Explanation: = 86 g/mol; 0.42/86 mol × 22400 = 109 mL.
Question 71
Chemistry · 4 marks · −1Consider the following reactions: A + NaCl + + Side Products (A in little amount). (Vapour) + NaOH B + NaCl + . B + C + . The number of terminal 'O' present in the compound 'C' is ______.
Correct answer: 6
Explanation: B = , C = (dichromate): 6 terminal O.
Question 72
Chemistry · 4 marks · −1The number of optical isomers exhibited by the iron complex (A) obtained from the following reaction is ______.
Correct answer: 2
Explanation: exists as a pair of enantiomers: 2.
Question 73
Chemistry · 4 marks · −10.5 g of an organic compound on combustion gave 1.46 g of and 0.9 g of . The percentage of carbon in the compound is ______. (Nearest integer) [Given : Molar mass (in g ) C : 12, H : 1, O : 16]
Correct answer: 80
Explanation: C = 1.46 × 12/44 = 0.398 g → 79.6% ≈ 80.
Question 74
Chemistry · 4 marks · −1Given : [C (graphite)] = 710 kJ , = 414 kJ , = 436 kJ , = 611 kJ . The for is ______ kJ (nearest integer value)
Correct answer: 25
Explanation: .