Question

The number of oxygen atom in borax which do not form $p\pi -p\pi$ backbonding are:

Answer 1

$\text{Borax}N{a}_2\left[B_4{O}_5\right(OH{)}_4].8H_{2}O$


$s{p}^2$ hybridised boron atom only participate in $p\pi -p\pi$ backbonding. So, the number of such boron atoms is $2$
Marked oxygen does not take part in $p\pi -p\pi$ backbonding.