Question

In which of the molecules lone pair, bond pair of electrons ratio is 2:3 ?

• A. Cl\(_2\)
• B. O\(_2\)
• C. HCl
• D. N\(_2\)

Hint:

Drawing the Lewis structure is essential for this type of question. Remember to count bonding pairs based on the bond order: a single bond is 1 pair, a double bond is 2 pairs, and a triple bond is 3 pairs.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
We need to find the molecule from the given options where the ratio of the total number of lone pairs of electrons to the total number of bonding pairs of electrons is 2:3.

Step 2: Key Formula or Approach:
For each molecule, we will draw the Lewis structure to determine the number of lone pairs and bonding pairs. A bonding pair is a pair of electrons shared between two atoms (a single bond is 1 BP, a double bond is 2 BP, a triple bond is 3 BP). A lone pair is a pair of valence electrons that is not shared.

Step 3: Detailed Explanation:
Let's analyze each molecule:
-

(A) Cl\(_2\): The Lewis structure is :Cl-Cl:. Each chlorine atom has 3 lone pairs, and there is 1 single bond between them.
- Total Lone Pairs (LP) = 3 + 3 = 6
- Total Bonding Pairs (BP) = 1
- Ratio LP:BP = 6:1.
-

(B) O\(_2\): The Lewis structure is :O=O:. Each oxygen atom has 2 lone pairs, and there is 1 double bond between them.
- Total LP = 2 + 2 = 4
- Total BP = 2 (a double bond counts as two pairs)
- Ratio LP:BP = 4:2 = 2:1.
-

(C) HCl: The Lewis structure is H-Cl:. The chlorine atom has 3 lone pairs, hydrogen has none. There is 1 single bond.
- Total LP = 3
- Total BP = 1
- Ratio LP:BP = 3:1.
-

(D) N\(_2\): The Lewis structure is :N\(\equiv\)N:. Each nitrogen atom has 1 lone pair, and there is 1 triple bond between them.
- Total LP = 1 + 1 = 2
- Total BP = 3 (a triple bond counts as three pairs)
- Ratio LP:BP = 2:3.
This matches the required ratio.

Step 4: Final Answer:
The molecule with a lone pair to bond pair ratio of 2:3 is N\(_2\).