MCQs on Class 11 Chemistry Chapter 2 | Structure of Atom MCQs for NEET 2021

1 Chlorine exists in two isotopic forms, Cl-37 and Cl-35 but its atomic mass is 35.5. This indicates the ratio of Cl-37 and Cl-35 is approximately

A 1:2

B 1:1

C 1:3

D 3:1

View Answer

Answer:1:3

2 Total number of orbitals associated with third shell will be __________.

A 2

B 4

C 9

D 3

View Answer

Answer:9

3 Two atoms are said to be isobars if.

A they have same atomic number but different mass number.

B they have same number of electrons but different number of neutrons.

C they have same number of neutrons but different number of electrons.

D sum of the number of protons and neutrons is same but the number of protons is different.

View Answer

Answer:sum of the number of protons and neutrons is same but the number of protons is different.

4 Which of the following properties of atom could be explained correctly by Thomson Model of atom?

A Overall neutrality of atom.

B Spectra of hydrogen atom.

C Position of electrons, protons and neutrons in atom.

D Stability of atom.

View Answer

Answer:Overall neutrality of atom.

5 Which of the following statements about the electron is incorrect?

A It is a negatively charged particle.

B The mass of electron is equal to the mass of neutron.

C It is a basic constituent of all atoms.

D It is a constituent of cathode rays.

View Answer

Answer:The mass of electron is equal to the mass of neutron.

6 Which of the following statement is not correct about the characteristics of cathode rays?

A They start from the cathode and move towards the anode.

B They travel in straight line in the absence of an external electrical or magnetic field.

C Characteristics of cathode rays do not depend upon the material of electrodes in cathode ray tube.

D Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube.

View Answer

Answer:Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube.

7 The probability density plots of 1s and 2s orbitals are given in Fig

Structure of Atom

The density of dots in a region represents the probability density of finding electrons in the region.

On the basis of above diagram which of the following statements is incorrect?

A 1s and 2s orbitals are spherical in shape.

B The probability of finding the electron is maximum near the nucleus.

C The probability of finding the electron at a given distance is equal in all directions.

D The probability density of electrons for 2s orbital decreases uniformly as distance from the nucleus increases.

View Answer

Answer:The probability density of electrons for 2s orbital decreases uniformly as distance from the nucleus increases.

8 Which of the following options does not represent ground state electronic configuration of an atom?

A 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸ 4s²

B 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁹ 4s²

C 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹

D 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹

View Answer

Answer:1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁹ 4s²

9 Which of the following conclusions could not be derived from Rutherford’s α -particle scattering experiment?

A Most of the space in the atom is empty.

B The radius of the atom is about 10–10 m while that of nucleus is 10–15 m.

C Electrons move in a circular path of fixed energy called orbits.

D Electrons and the nucleus are held together by electrostatic forces of attraction.

View Answer

Answer:Electrons move in a circular path of fixed energy called orbits.

10 In which of the following pairs, the ions are iso-electronic?

A Na⁺, Mg²⁺

B Al³⁺, O^–

C Na⁺, O^2-

D N3^–, Cl^–

View Answer

Answer:C, D

11 Maximum number of electrons in a subshell with l = 3 and n = 4 is

A 10

B 12

C 14

D 16

View Answer

Answer:14

12 The correct set of four quantum numbers for the valence electron of rubidium atom (Z = 37) is

A 5, 0, 0, + 1/2

B 5, 1, 0, + 1/2

C 5, 1, 1, + 1/2

D 6, 0, 0, + 1/2

View Answer

Answer:5, 0, 0, + 1/2

13 Identify the wrong statement in the following

A Atomic radius of the elements increases as one moves down the first group of the periodic table

B Atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the

C Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius

D Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius

View Answer

Answer:Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius

14 A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emissions is at 680 nm, the other is at: [AIEEE 2011]

A 518 nm

B 1035 nm

C 325 nm

D 743 nm

View Answer

Answer:743 nm

15 The energy of an electron in first Bohr orbit of H-atom is –13.6 eV. The possible energy value of electron in the excited state of Li²⁺ is [West Bengal JEE 2011]

A – 122.4 eV

B 30.6 eV

C – 30.6 eV

D 13.6 eV

View Answer

Answer: – 30.6 eV

16 The electronic transitions from n = 2 to n = 1 will produce shortest wavelength in (where n = principal quantum state) [West Bengal JEE 2011]

A Li⁺²

B He⁺

C H

D H⁺

View Answer

Answer:Li⁺²

17 The energy required to break one mole of Cl – Cl bonds in Cl₂ is 242 kJ mol^–1. The longest wavelength of light capable of breaking a single Cl – Cl bond is

(c = 3×108 ms^–1 and NA = 6.02×1023 mol^–1)

A 594 nm

B 640 nm

C 700 nm

D 494 nm

View Answer

Answer:494 nm

18 Mg²⁺ is isoelectronic with

A Ca²⁺

B Na⁺

C Zn²⁺

D Cu²⁺

View Answer

Answer: Na⁺

19 Which one of the following sets of ions represents a collection of isoelectronic species?

A K⁺, Cl^–, Ca²⁺, Sc³⁺

B Ba²⁺, Sr²⁺, K⁺, S^2–

C N^3–, O^2–, F^–, S^2–

D Li⁺, Na⁺, Mg²⁺, Ca²⁺

View Answer

Answer:K⁺, Cl^–, Ca²⁺, Sc³⁺

20 Consider the ground state of Cr atom (Z = 24). The numbers of electrons with the azimuthal quantum numbers, l = 1 and 2 are, respectively: [AIEEE 2004]

A 12 and 4

B 12 and 5

C 16 and 4

D 16 and 5

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