Q8 / 200 · WBJEE 2014 · Chemistry
The correct order of decreasing $\mathrm{H}-\mathrm{C}-\mathrm{H}$ angle in the following molecule is


- AI>II>III
- Correct answerBII>I>III
- CIII>II>I
- DI>III>II
Solution
$\mathrm{H}-\mathrm{C}-\mathrm{H}$ bond angle is about $120^{\circ}$, when $\mathrm{C}$ is bonded through a double bond but in case of $\mathrm{CH}_{4}$ the $\mathrm{H}-\mathrm{C}-\mathrm{H}$ bond angle is only $109^{\circ} \mathrm{2B}^{\prime}$
Cyclic compounds have a $\mathrm{H}-\mathrm{C}-\mathrm{H}$ bond angle Feater than $109^{\circ} 28^{\prime}$ due to hindrance. Thus, the correct order of $1 \mathrm{H}-\mathrm{C}-\mathrm{H}$ bond angle is


Hence, the correct answer is option: 'B'.