Give reasons for the following :
'Carbon-oxygen bond lengths in formic acid aer `1.23 Å` and `1.36 Å` and both carbon-oxygen bonds in sodium formate have the same value, i.e., `1.27 Å`.

Explanation

In sodium formate, the contributing structures for the anion are equivalent while these are not the same in formic acid. Thus, carbon-oxygen bond length in formate ion is the same for both the bonds while these are different in formic acid.