Practice Questions

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: 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.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.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.A solution is prepared by adding 2 g of ′′X′′ to 1 mole of water. Mass percent of ′′X′′in solution is (1) 5% (2) 20% (3) 2% (4) 10% JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper

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.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 number of following statement/s which is/are incorrect is ______ A) Line emission spectra are used to study the electronic structure B) The emission spectra of atoms in the gas phase show a continuous spread of wavelength from red to violet. C) An absorption spectrum is like the photographic negative of an emission spectrum D) The element helium was discovered in the sun by spectroscopic method

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.Which of the following options are correct for the reaction? - 2 - 2Au ( CN ) 2 (aq) + Zn(s) →2Au(s) + Zn ( CN ) 4 (aq) A. Redox reaction B. Displacement reaction C. Decomposition reaction D. Combination reaction Choose the correct answer from the options given below: (1) A only (2) A and D only (3) A and B only (4) C and D only

Q32.Given below are two statements: Statement I: The decrease in first ionization enthalpy from B to Al is much larger than that from Al to Ga. Statement II: The d orbitals in Ga are completely filled. In the light of the above statements, choose the most appropriate answer from the options given below JEE Main 2023 (29 Jan Shift 2) JEE Main Previous Year Paper (1) Statement I is incorrect but statement II is (2) Both the statements I and II are correct correct. (3) Statement I is correct but statement II is incorrect (4) Both the statements I and II are incorrect

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

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.Given below are two statement : one is labelled as Assertion A and the other is labelled as Reason R Assertion A : 5f electron can participate in bonding to a far greater extent than 4f electrons Reason R : 5f orbitals are not as buried as 4f orbitals In the light of the above statements, choose the correct answer from the options given below (1) A is false but R is true (2) Both A and R are true and R is the correct explanation of A (3) A is true but R is false (4) Both A and R are true but R is NOT the correct explanation of A

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

Q32.What is the number of unpaired electron(s) in the highest occupied molecular orbital of the following species : N2, N +2 , O2, O+2 ? (1) 0, 1, 2, 1 (2) 2, 1, 2, 1 (3) 0, 1, 0, 1 (4) 2, 1, 0, 1

Q32.The total number of lone pairs of electrons on oxygen atoms of ozone is

Q32.Maximum number of electrons that can be accommodated in shell with n = 4 are: (1) 16 (2) 32 (3) 50 (4) 72

Q32.The number of given orbitals which have electron density along the axis is px, py, pz, dxy, dyz, dxz, d2z, dx2−y2

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.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.Assume carbon burns according to following equation : 2C(s) + O2( g) →2 CO (s) when 12 g carbon is burnt in 48 g of oxygen, the volume of carbon monoxide produced is ______ × 10−1 L at STP [nearest integer] [Given : Assume CO as ideal gas, Mass of C is 12 g mol−1 , mass of O is 16 g mol−1 and molar volume of an idal gas at STP is 22. 7 L mol−1 ]

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

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 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 -