Question

The correct order of increasing bond lengths of C--H, O--H, C--C, and H--H is

• A. O--H $<$ H--H $<$ C--C $<$ C--H
• B. C--C $<$ C--H $<$ H--H $<$ O--H
• C. C--C $<$ O--H $<$ H--H $<$ C--H
• D. H--H $<$ O--H $<$ C--H $<$ C--C

Hint:

Bond lengths increase with the size of the atoms involved and decrease with higher bond orders; single bonds between larger atoms (like C--C) are longer than those involving smaller atoms (like H--H).

Answer 1

The Correct Option is D

Let’s break this down step by step to determine the correct order of bond lengths and why option (4) is the correct answer.
Step 1: Understand the factors affecting bond lengths 
Bond length depends on: 

• The size of the atoms involved (larger atoms form longer bonds).
• The bond order (higher bond order results in shorter bonds).

Typical bond lengths (in pm): 

• H--H: 74 pm (in H$_2$, single bond).
• O--H: $\sim$96 pm (in H$_2$O, single bond).
• C--H: $\sim$109 pm (in CH$_4$, single bond).
• C--C: $\sim$154 pm (in C$_2$H$_6$, single bond).

Step 2: Compare the bond lengths 

• H--H: Smallest, as both atoms are hydrogen, 74 pm.
• O--H: Oxygen is larger than hydrogen, $\sim$96 pm.
• C--H: Carbon is larger than oxygen, $\sim$109 pm.
• C--C: Two carbon atoms, single bond, longest at $\sim$154 pm.

Order of increasing bond lengths: 
\[ \text{H--H}<\text{O--H}<\text{C--H}<\text{C--C} \] 
Step 3: Confirm the correct answer 
The order matches option (4). 
Thus, the correct answer is (4) H--H $<$ O--H $<$ C--H $<$ C--C.