Question

Which of the following is correct decreasing order of bond length regarding $N_{2}$, $O_{2}$ and $Cl_{2}$?

• A. $Cl_{2} > O_{2} > N_{2}$
• B. $Cl_{2} > N_{2} > O_{2}$
• C. $O_{2} > N_{2} > Cl_{2}$
• D. $N_{2} > O_{2} > Cl_{2}$

Hint:

Single Bond > Double Bond > Triple Bond (Length).

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
Bond length is inversely proportional to the bond order (number of bonds between atoms) and directly proportional to the size of the atoms.

Step 3: Detailed Explanation:
- \( \text{N}_2 \): Triple bond (\( \text{N} \equiv \text{N} \)), bond order \( = 3 \). Small atomic size. Shortest bond.
- \( \text{O}_2 \): Double bond (\( \text{O}=\text{O} \)), bond order \( = 2 \). Small atomic size.
- \( \text{Cl}_2 \): Single bond (\( \text{Cl}-\text{Cl} \)), bond order \( = 1 \). Chlorine atoms are much larger than N and O.
As bond order increases, bond length decreases.
Order based on bond order: Single bond \( > \) Double bond \( > \) Triple bond.
Also, atomic radius of Cl \( > \) O \( > \) N.
Thus, the decreasing order of bond length is \( \text{Cl}_2 > \text{O}_2 > \text{N}_2 \).

Step 4: Final Answer:
The correct order is \( \text{Cl}_2 > \text{O}_2 > \text{N}_2 \).