WBCS Mains Chemistry Atoms & Molecules Questions 2023

Q. Law of definite proportion is obeyed in
(A) Stoichiometry
(B) Electrometry
(C) Photometry
(D) Spectrometer

Correct Answer: (A) Stoichiometry

Q. Which structure has delocalized π electrons?
(A) O₃
(B) CO
(C) HCN
(D) CO₂

Correct Answer: (A) O₃

Q. Fullerene is made up of ______ carbon atoms
(A) 100
(B) 20
(C) 75
(D) 60

Correct Answer: (D) 60

Q. What is the order of increasing energy of the orbitals within a single energy level?
(A) d < s < f < p
(B) s < p < d < f
(C) p < s < f < d
(D) f < d < p < s

Correct Answer: (B) s < p < d < f

Q. Which species does not contain at least one 90° bond angle?
(A) CF₄
(B) PF₅
(C) SF₆
(D) SiF₆²⁻

Correct Answer: (A) CF₄

Q. Graphite is a good conductor of electricity due to
(A) Strong electrostatic bonding
(B) Free localized bonds
(C) Free delocalized electrons
(D) Tetrahedral arrangement of particles

Correct Answer: (C) Free delocalized electrons

WBCS Mains Chemistry Atoms & Molecules Questions 2022

Q. Metallic bond is not characterised by
(A) Opacity
(B) Ductility
(C) High conductivity
(D) Directionality

Correct Answer: (D) Directionality

Q. Which type of bond is present in superhard material tungsten carbide?
(A) Ionic
(B) Covalent
(C) Metallic
(D) All of the above

Correct Answer: (D) All of the above

WBCS Mains Chemistry Atoms & Molecules Questions 2021

Q. Carbon, diamond and graphite are together called
(A) Allotrope
(B) Isomers
(C) Isotopes
(D) Isobars

Correct Answer: (A) Allotrope

Q. The number of moles of solute present in 1 kg of a solvent is called
(A) Molality
(B) Molarity
(C) Normality
(D) Solubility

Correct Answer: (A) Molality

Q. The present atomic weight scale is based on
(A) C-12
(B) H-1
(C) C-13
(D) O-16

Correct Answer: (A) C-12

WBCS Mains Chemistry Atoms & Molecules Questions 2020

Q. Diamond and graphite are allotropes of
(A) Iron
(B) Gold
(C) Carbon
(D) Copper

Correct Answer: (C) Carbon

Q. What is the typical size of an atom?
(A) 1 meter
(B) 10⁻² meter
(C) 10⁻⁶ meter
(D) 10⁻¹⁰ meter

Correct Answer: (D) 10⁻¹⁰ meter

Q. How many atoms are there in one mole atom of an element?
(A) 5.015 × 10¹⁵
(B) 6.022 × 10²³
(C) 4.397 × 10²⁶
(D) 6.589 × 10²⁰

Correct Answer: (B) 6.022 × 10²³

Q. In the Rutherford experiment towards the discovery of atomic nucleus, the target used was
(A) Gold
(B) Silver
(C) Platinum
(D) Copper

Correct Answer: (A) Gold

Q. Number of valence electrons in Cl⁻ ion are
(A) 16
(B) 8
(C) 17
(D) 18

Correct Answer: (B) 8

Q. The number of neutrons in Hydrogen nucleus is
(A) 0
(B) 1
(C) 2
(D) 3

Correct Answer: (A) 0

Q. Two isotopes have same
(A) Mass number
(B) Difference of neutron number and proton number
(C) Neutron number
(D) Proton number

Correct Answer: (D) Proton number

WBCS Mains Chemistry Atoms & Molecules Questions 2019

Q. Which of the following does not have coordinate bond?
(A) SO₂
(B) HNO₂
(C) HNO₃
(D) H₂SO₃

Correct Answer: (B) HNO₂

Q. Which of the following configurations corresponds to the element of highest ionisation energy?
(A) 1s², 2s¹
(B) 1s², 2s², 2p³
(C) 1s², 2s², 2p²
(D) 1s², 2s², 2p⁶, 3s¹

Correct Answer: (B) 1s², 2s², 2p³

WBCS Mains Chemistry Atoms & Molecules Questions 2018

Q. Carbon atom in benzene molecule is
(A) sp hybridised
(B) sp² hybridised
(C) sp³ hybridised
(D) Not hybridised

Correct Answer: (B) sp² hybridised

Q. Which is the hardest material of the following?
(A) Corundum
(B) Diamond
(C) SiC
(D) B₄C

Correct Answer: (B) Diamond

Q. The chemical bonding in diamond is
(A) Covalent
(B) Ionic
(C) Coordinate
(D) Metallic

Correct Answer: (A) Covalent

Q. Atomic defect responsible for reduction of bulk density of the material is
(A) Schottky
(B) Frenkel
(C) Interstitial
(D) Electronic

Correct Answer: (A) Schottky

Q. The crystal having cell dimensions, a ≠ b ≠ c, (α = β = γ = 90°) has structure
(A) Tetragonal
(B) Orthorhombic
(C) Triclinic
(D) Monoclinic

Correct Answer: (B) Orthorhombic

Q. Which of the following possesses zero dipole moment?
(A) NH₃
(B) CCl₄
(C) BF₃
(D) H₂O

Correct Answer: (B) CCl₄

WBCS Mains Chemistry Atoms & Molecules Questions 2017

Q. 4.4 g of CO₂ occupies how many litres of CO₂ at STP?
(A) 2.4
(B) 2.24
(C) 44
(D) 22.4

Correct Answer: (B) 2.24

Q. Number of unpaired electrons present in Cu²⁺ is
(A) 3
(B) 5
(C) 1
(D) 7

Correct Answer: (C) 1

Q. The structure of α-alumina is
(A) Trigonal
(B) Orthorhombic
(C) Hexagonal
(D) Cubic

Correct Answer: (C) Hexagonal

Q. Martensitic steel has the following crystal structure:
(A) BCC
(B) FCC
(C) BCT
(D) HCP

Correct Answer: (C) BCT

WBCS Mains Chemistry Atoms & Molecules Questions 2016

Q. The number of unpaired electrons in Mn²⁺ is

(A) 1
(B) 3
(C) 4
(D) 5

Correct Answer: (D) 5