Question

In the series, ethane , ethylene & acetylene, the carbon-hydrogen bond length is :

• A. equal in all the three
• B. largest in ethane
• C. smallest in ethylene
• D. largest in acetylene

Answer 1

The correct option is B largest in ethane

In ethane $\left(C{H}_{3}C{H}_3\right)$, $C-H$ bond length is $111.0$ pm.

In ethylene $(C{H}_2=C{H}_2)$, $=C-H$ bond length is $110.3$ pm.

In acetylene $(CH\equiv CH)$ , $\equiv C-H$ bond length is $108$ pm.

So order of $C-H$ bond length is as follows:

ethane $>$ ethylene $>$ acetylene

So answer is B.