Question

The $C-H$ and $C-C$ bond distance are shortest in

• A. methane
• B. ethane
• C. ethene
• D. ethyne

Answer 1

Answer: (D)

Due to smaller size of $sp$-orbital (as compared to $s{p}^2$ (in ethene) or
$s{p}^3$ (in methane and ethane))
$C-H(1.06\mathring{A})$ and
$C-C(1.20\mathring{A})$
distance are the shortest in ethyne.