Solution :
$${C_2}{H_6}$$ is a saturated hydrocarbon and its carbon is $$s{p^3}$$ hybridised. Hence it is least electronegative among alkanes, alkenes and akynes with the result $$C - H$$ bond length will be maximum.
Releted MCQ Question on Organic Chemistry >> General Organic Chemistry
Releted Question 1
The bond order of individual carbon-carbon bonds in
benzene is