Question

Give reason:
Molecules of hydrogen and chlorine have single covalent bonds between their atoms while oxygen has a double covalent and nitrogen a triple covalent bond respectively.

Answer 1

Chlorine and Hydrogen both have 1 valency so they can gain or share 1 electron to complete their valence shell , so they form single bonds.
Valency of oxygen is 2 so it needs to gain or share 2 electrons so it forms double bond .
Valency of Nitrogen is 3 so it needs to gain or share 3 electrons so it forms a triple bond.

Answer 2

Answer:

Chlorine and Hydrogen both have a valency of 1 so they can gain or share 1 electron to complete their valence shell.

Therefore they form single bonds.

Oxygen has valency of 2 so it can gain or share 2 electrons to complete its valence shell.

Therefore it forms a double bond.

Nitrogen has valency of 3 so it can gain or share 3 electrons to complete its valence shell.

Therefore it forms a triple bond.