250+ TOP MCQs on Bonding in Some Homonuclear Diatomic Molecules and Answers

Chemistry Multiple Choice Questions on “Bonding in Some Homonuclear Diatomic Molecules”.

1. What is the electronic configuration of hydrogen molecule?
a) σ1s²
b) σ1s¹
c) σ1s
d) σ*1s
Answer: a
Clarification: In a hydrogen atom, each hydrogen shares an electron from 1s orbital, so in total there are two electrons present in 1s bonding orbital of the molecule. So the electronic configuration of the hydrogen molecule is σ1s².

2. What is the condition, for a molecule do not exist?
a) N_A = N_B
b) N_A > N_B
c) N_A < N_B
d) N_A >/< N_B
Answer: a
Clarification: When a molecule’s bond order is equal to zero, the molecule cannot exist. The formula for finding out bond order is (frac{1}{2})(N_B – N_A). So N_A – N_B = 0, that is N_A = N_B. Where N_A as the number of anti-bonding molecular orbitals and N_B as the number of bonding molecular orbitals.

3. Which of the following molecule doesn’t exist?
a) O₂
b) H₂
c) He₂
d) N₂
Answer: b
Clarification: The electronic configuration of He₂ is σ1s²σ*1s². Here N_A = N_B (where N_A as the number of anti-bonding molecular orbitals and N_B as the number of bonding molecular orbitals). So the molecule He₂ doesn’t exist.

4. The number of electrons in bonding orbital and anti-bonding orbital of Lithium molecule are ______ and _______ respectively.
a) 4, 4
b) 2, 2
c) 2, 4
d) 4, 2
Answer: d
Clarification: The lithium molecule is denoted by Li₂. When the lithium molecule is formed, each of the lithium shares an electron in the 2s orbital. Its electronic configuration is σ1s²σ*1s²σ2s². So the number of electrons in bonding orbital and anti-bonding orbital of Lithium molecule are 4 and 2 respectively.

5. What is the electronic configuration of the carbon atom?
a) 1s²2s²2p²
b) σ1s²σ*1s²σ2s²σ*2s²π2p_x²π2p_y²
c) 1s²2s²2p¹
d) σ1s²σ*1s σ2s²π2p_x²π2p_y²
Answer: a
Clarification: The given question electronic configuration of carbon “atom”, but not carbon “molecule”. So by following Aufbau’s principle and noting that carbon contains 6 electrons, the answer is given as 1s²2s²2p².

6. O₂ is paramagnetic in nature.
a) True
b) False
Answer: a
Clarification: σ1s²σ*1s²σ2s²σ*2s²2p_z²π2p_x²π2_y²π*2p_x¹π*2p_y¹ is the electronic configuration of O₂ molecule. According to this, it has two unpaired electrons, making it paramagnetic and is attracted by the magnetic field.

7. The electronic configurations of molecules change when the number of electrons is ________
a) 10
b) 20
c) 17
d) 14
Answer: d
Clarification: The electronic configuration below number of electrons = 14, i.e. number of electrons = 12 is σ1s²σ*1s²σ2s² σ*2s²π2p_x²π2_y²but after 14, take number of electrons = 16 is σ1s²σ*1s²σ2s²σ*2s²2p_z²π2p_x²π2_y²π*2p_x¹π*2p_y¹ So the change comes near 2p_z orbital’s place.

8. Which of the following is true regarding nitrogen molecule.
a) Diamagnetic
b) Paramagnetic
c) Bond order is 2
d) Total number of electrons in the molecule is 13
Answer: a
Clarification: The Nitrogen molecule N₂ is diamagnetic in nature as it contains zero single electrons, all the electrons are paired. Its bond order is calculated as 3 and the total number of electrons the nitrogen molecule are 14.

9. H₂, N₂, O₂ and Li₂ are ______________
a) heteronuclear diatomic molecules
b) heteronuclear triatomic molecules
c) homonuclear diatomic molecules
d) homonuclear triatomic molecules
Answer: c
Clarification: The molecules that have the same atoms in them are called as homonuclear molecules. The molecules that have only two atoms are called diatomic molecules. So H₂, N₂, O₂, and Li₂ are called homonuclear diatomic molecules.

10. What is the total number of electrons in the Chlorine molecule?
a) 17
b) 34
c) 18
d) 16
Answer: b
Clarification: A Chlorine atom is made up of 17 electrons. When two Chlorine atoms share an electron covalently, the Chlorine molecule is formed. So the Chlorine molecule Cl₂ has a total of 17 + 17 atoms = 34 atoms.