Practice Questions

Q30.The decay constant for a radioactive nuclide is 1 . 5 × 10-5 s-1. Atomic weight of the substance is 60 g mole-1, 𝑁𝐴= 6 × 1023. The activity of 1 . 0 µ g of the substance is ________ × 1010 Bq.

Q30.When two resistance R1 and R2 connected in series and introduced into the left gap of a meter bridge and a resistance of 10 Ω is introduced into the right gap, a null point is found at 60 cm from left side. When R1 and R2 are connected in parallel and introduced into the left gap, a resistance of 3 Ω is introduced into the right- gap to get null point at 40 cm from left end. The product of R1 R2 is ______ Ω2

Q30.Statement I : When a Si sample is doped with Boron, it becomes P type and when doped by Arsenic it becomes N-type semi conductor such that P-type has excess holes and N-type has excess electrons. Statement II : When such P-type and N-type semi-conductors, are fused to make a junction, a current will automatically flow which can be detected with an externally connected ammeter. In the light of above statements, choose the most appropriate answer from the options given below. (1) Both Statement I and statement II are incorrect (2) Statement I is incorrect but statement II is correct (3) Both Statement I and statement II are correct (4) Statement I is correct but statement II is incorrect

Q30.A light of energy 12 . 75 eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is 𝑥 – 15 – 𝜋× 10-17 eVs. The value of 𝑥 is ______ (use ℎ= 4 . 14 × 10 eVs, 𝑐= 3 × 108 m s 1)

Q30.In a metre bridge experiment the balance point is obtained if the gaps are closed by 2 Ω and 3 Ω. A shunt of X Ω is added to 3 Ω resistor to shift the balancing point by 22. 5 cm. The value of X is ______.

Q30.The amplitude of 15 sin(1000 πt) is modulated by 10 sin(4 πt) signal. The amplitude modulated signal contains frequencies of A. 500 Hz B. 2 Hz C. 250 Hz D. 498 Hz E. 502 Hz Choose the correct answer from the options given below JEE Main 2023 (12 Apr Shift 1) JEE Main Previous Year Paper (1) A and B only (2) A and C only (3) A and D only (4) A, D and E only

Q31.Number of hydrogen atoms per molecule of a hydrocarbon A having 85. 8% carbon is (Given : Molar mass of A = 84 g mol−1 )

Q31.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: 3 . 1500 𝑔 of hydrated oxalic acid dissolved in water to make 250 . 0 𝑚𝐿 solution will result in 0 . 1 𝑀 oxalic acid solution. Reason R: Molar mass of hydrated oxalic acid is 126 𝑔 𝑚𝑜𝑙– 1 . In the light of the above statements, choose the correct answer from the options given below: (1) Both A and R are true but R is NOT the correct (2) A is true but R is false explanation of A (3) Both A and R are true and R is the correct (4) A is false but R is true explanation of A

Q31.The radius of the 2nd orbit of Li2+ is x . The expected radius of the 3rd orbit of Be3+ is (1) 9 4 x (2) 94 x (3) 27 16 x (4) 2716 x JEE Main 2023 (25 Jan Shift 1) JEE Main Previous Year Paper

Q31.Which transition in the hydrogen spectrum would have the same wavelength as the Balmer type transition from n = 4 to n = 2 of He+spectrum (1) n = 2 to n = 1 (2) n = 1 to n = 3 (3) n = 1 to n = 2 (4) n = 3 to n = 4

Q31.For a concentrated solution of a weak electrolyte (Keq = equilibrium constant) A2B3 of concentration ‘C’, the degree of dissociation ‘α’ is (1) Keq 15 (2) Keq 15 5c4 108c4 (3) Keq 15 (4) Keq 15 25c2 6c5 JEE Main 2023 (06 Apr Shift 1) JEE Main Previous Year Paper

Q31.Following figure shows spectrum of an ideal black body at four different temperatures. The number of correct statement/s from the following is _______. JEE Main 2023 (24 Jan Shift 2) JEE Main Previous Year Paper A. T4 > T3 > T2 > T1 B. The black body consists of particles performing simple harmonic motion. C. The peak of the spectrum shifts to shorter wavelength as temperature increases. D. T1 = T2 = T3 ν1 ν2 ν3 E. The given spectrum could be explained using quantisation of energy

Q31.Given below are two statements Statement I : According to Bohr’s model of hydrogen atom, the angular momentum of an electron in a given stationary state is quantised. Statement II : The concept of electron in Bohr’s orbit, violates the Heisenberg uncertainty principle. In the light of the above statements, choose the most appropriate answer from the options given below (1) Statement I is incorrect but Statement II is (2) Both Statement I and Statement II are correct correct (3) Both Statement I and Statement II are incorrect (4) Statement I is correct but Statement II is incorrect

Q31.When a hydrocarbon A undergoes complete combustion it requires 11 equivalents of oxygen and produces 4 equivalents of water. What is the molecular formula of A? (1) C11H8 (2) C11H4 (3) C5H8 (4) C9H8

Q31.The molality of a 10%(v/V) solution of di-bromine solution in CCl4 (carbon tetrachloride) is x '. x = _____ × 10−2M. (Nearest integer) [Given : molar mass of Br2 = 160 g mol−1 atomic mass of C = 12 g mol−1 atomic mass of Cl = 35. 5 g mol−1 density of dibromine = 3. 2 g cm−3 density of CCl4 = 1. 6 g cm−3]

Q31.The wave function (Ψ) of 2 s is given by 1/2 − Ψ2s = a0 1 ( a01 ) (2 r )e−r/2a0 2√2π At r = r0 , radial node is formed. Thus, r0 in terms of a0 (1) r0 = a0 (2) r0 = 4a0 (3) r0 = a02 (4) r0 = 2a0

Q31.A metal chloride contains 55. 0% of chlorine by weight. 100 mL vapours of the metal chloride at STP weigh 0. 57 g . The molecular formula of the metal chloride is (Given: Atomic mass of chlorine is 35. 5 u ) (1) MCl4 (2) MCl3 (3) MCl2 (4) MCl

Q31.If the radius of the first orbit of hydrogen atom is a0 , then de Broglie’s wavelength of electron in 3rd orbit is (1) πa0 (2) πa0 6 3 (3) 6πa0 (4) 3πa0

Q31.The shortest wavelength of hydrogen atom in Lyman series is λ. The longest wavelength in Balmer series of He+ is (1) 5 (2) 9λ 9λ 5 (3) 36λ (4) 5λ 5 9

Q31.An organic compound gives 0. 220 g of CO2 and 0. 126 g of H2O on complete combustion. If the % of carbon is 24 then the % of hydrogen is _________ × 10–1. (Nearest integer)

Q32.Henry Moseley studied characteristic X-ray spectra of elements. The graph which represents his observation correctly is Given v = Frequency of X-ray emitted Z = Atomic number JEE Main 2023 (08 Apr Shift 2) JEE Main Previous Year Paper (1) (2) (3) (4)

Q32.Match List-I with List-II List-I List-II A 16 g of CH4 ( g ) I Weighs 28g B 1 g of H2 ( g ) II 60 . 2 × 1023 electrons C 1 mole of N2 ( g ) III Weighs 32g D 0 . 5 mol of SO2 ( g ) IV Occupies11 . 4 L volume at STP Choose the correct answer from the options given below: JEE Main 2023 (10 Apr Shift 2) JEE Main Previous Year Paper (1) A-II, B-III, C-IV, D-I (2) A-II, B-IV, C-I, D-III (3) A-I, B-III, C-II, D-IV (4) A-II, B-IV, C-III, D-I

Q32.The correct increasing order of the ionic radii is (1) Cl- < Ca2 + < K+ < S2 - (2) K+ < S2 - < Ca2 + < Cl- (3) S2 - < Cl- < Ca2 + < K+ (4) Ca2 + < K+ < Cl- < S2 -

Q32.For OF2 molecule consider the following: (A) Number of lone pairs on oxygen is 2. (B) FOF angle is less than 104 . 5°. (C) Oxidation state of O is -2. (D) Molecule is bent 'V' shaped. (E) Molecular geometry is linear. Correct options are: (1) C, D, E only (2) B, E, A only (3) A, C, D only (4) A, B, D only

Q32.Decreasing order of the hydrogen bonding in following forms of water is correctly represented by A. Liquid water B. Ice C. Impure water (1) A = B > C (2) B > A > C (3) C > B > A (4) A > B > C