Arrange the following compounds in increasing order of C-OH bond length:
methanol, phenol, p-ethoxyphenol

Options

A. `" phenol" lt "methanol" lt "p-methoxyphenol"`
B. `"methanol" lt "p-methoxyphenol" lt " phenol"`
C. `" phenol" lt "p-methoxyphenol" lt "methanol"`
D. `"methanol" lt " phenol" lt "p-methoxyphenol"`

Answer

C

Explanation

In methanol, there is no resonance. In phenol, there is resonance. In p-Ethoxyphenol, there is resonance involved but the involvement of lone pair of oxygen in OH group is poor as compared with phenol due to the presence of lone pair oxygen in `OCH_(3)` group which are also involved in resonance.
So, partial double bond character develops in C-OH bond of phenol and p-ethoxyphenol but in case of p-ethoxyphenol, resonance is poor as compared to phenol. So, bond length follows the order : `"methanol" gt "p-ethoxyphenol" gt "phenol"`