Practice Questions

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.Match List - I with List - II LIST-II LIST-I (Block of periodic (Atomic number) table) (A) 37 I. p-block (B) 78 II. d-block JEE Main 2023 (30 Jan Shift 1) JEE Main Previous Year Paper (C) 52 III. f-block (D) 65 IV. s-block Choose the correct answer from the options given below: (1) A - II, B - IV, C - I, D - III (2) A - I, B - III, C - IV, D - II (3) A - IV, B - III, C - II, D - I (4) A - IV, B - II, C - I, D - III

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.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 number of molecules and moles in 2 . 8375 litres of O2 at STP are respectively (1) 7 . 527 × 1023 and 0 . 125 mol (2) 7 . 527 × 1022 and 0 . 250 mol (3) 1 . 505 × 1023 and 0 . 250 mol (4) 7 . 527 × 1022 and 0 . 125 mol

Q31.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Hydrogen is an environment friendly fuel. Reason R: Atomic number of hydrogen is 1 and it is a very light element. In the light of the above statements, choose the correct answer from the options given below (1) A is true but R is false (2) Both A and R are true but R is NOT the correct explanation of A (3) A is false but R is true (4) Both A and R are true and R is the correct explanation of A

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.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.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)

Q31.It is observed that characteristic X-ray spectra of elements show regularity. When frequency to the power 'n' i.e. vn of X-rays emitted is plotted against atomic number Z, the following graph is obtained. The value of 'n' is JEE Main 2023 (24 Jan Shift 1) JEE Main Previous Year Paper (1) 1 (2) 2 1 (3) (4) 3 2

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.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.Which of the following have same number of significant figures? (A) 0. 00253 (B) 1. 0003 (C) 15. 0 (D) 163 Choose the correct answer from the options given below (1) A, B and C only (2) C and D only (3) B and C only (4) A, C and D only

Q31.Assume that the radius of the first Bohr orbit of hydrogen atom is 0. 6Å . The radius of the third Bohr orbit of He+ is _____ picometer. (Nearest Integer)

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.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]

Q32.Consider the following statement (A) NF3 molecules has a trigonal planar structure. (B) Bond Length of N2 is shorter than O2 . (C) Isoelectronic molecules or ions have identical bond order. (D) Dipole moment of H2S is higher than that of water molecule. Choose the correct answer from the options given below: (1) (A) and (B) are correct (2) (A) and (D) are correct (3) (C) and (D) are correct (4) (B) and (C) are correct

Q32.The bond dissociation energy is highest for (1) Cl2 (2) I2 (3) Br2 (4) F2

Q32.The volume of hydrogen liberated at STP by treating 2. 4 g of magnesium with excess of hydrochloric acid is ...... ×10−2 L. Given Molar volume of gas is 22. 4 L at STP. Molar mass of magnesium is 24 g mol−1

Q32.The energy of an electron in the first Bohr orbit of hydrogen atom is −2. 18 × 10−18 J Its energy in the third Bohr orbit is _______. (1) 9 1 th of the value (2) 271 of this value (3) Three times of this value (4) One third of this value

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.Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R : Assertion A: In the photoelectric effect, the electrons are ejected from the metal surface as soon as the beam of light of frequency greater than threshold frequency strikes the surface. Reason R : When the photon of any energy strikes an electron in the atom, transfer of energy from the photon to the electron takes place. In the light of the above statements, choose the most appropriate answer from the options given below : (1) Both A and R are correct and R is the correct (2) A is correct but R is not correct explanation of A (3) Both A and R are correct but R is NOT the (4) A is not correct but R is correct correct explanation of A JEE Main 2023 (11 Apr Shift 1) JEE Main Previous Year Paper

Q32.Match Lis-I with List-II. List-1 List-II Hexamethylenediamine A. Weak intermolecular forces of attraction I. + adipic acid B. Hydrogen bonding II. AlEt3 + TiCl4 C. Heavily branched polymer III. 2 - chloro - 1, 3 - butadiene D. High density polymer IV. Phenol + formaldehyde Choose the correct answer from the options given below (1) A-IV, B-II, C-III, D-I (2) A-IV, B-I, C-III, D-II (3) A-II, B-IV, C-I, D-III (4) A-III, B-I, C-IV, D-II

Q32.Which one of the following elements will remain as liquid inside pure boiling water? JEE Main 2023 (06 Apr Shift 2) JEE Main Previous Year Paper (1) Ga (2) Br (3) Li (4) Cs

Q32.Match List I with List II (A) Slaked lime (I) NaOH (B) Dead burnt plaster (II) Ca ( OH ) 2 (C) Caustic soda (III) Na2CO3 · 10H2O (D) Washing soda (IV) CaSO4 Choose the correct answer form the options given below: (1) (A) - I, (B) - IV, (C) - II, (D) - III (2) (A) - III, (B) - IV, (C) - II, (D) - I (3) (A) - II, (B) - IV, (C) - I, (D) - III (4) (A) - III, (B) - II, (C) -IV, (D) -I