Question

If the bond length of C-Cl bond in chloromethane is 178pm, what will be the probable bond length of C-Br bond in bromomethane?

(a) 139pm

(b) 156pm

(c) 178pm

(d) 193pm

The question was asked during an online interview.

This question is from Nature of C-X Bond in section Haloalkanes and Haloarenes of Chemistry – Class 12

Answer 1

The correct choice is (d) 193pm

For explanation I would say: The size of Cl atom is smaller than the size of Br atom as the latter appears lower than Cl in the halogen group. Hence, the carbon-halogen bond length of C-Br must be bigger than that of C-Cl, i.e., 178pm, therefore it must be 193pm.