The novolac polymer has mass of 963g. The number of monomer units present in it are

Monomer of novolac is

Molecular mass of monomer unit

              = 12 * 7 + 1 * 8 + 16 * 2

              = 84 + 8 + 32

              = 124 g

Molecular mass of polymer = 963 g

$\therefore$ n * mass of monomer = mass of polymer + (n – 1) * 18

(n – 1) unit of H₂O is removed during formation

$\therefore 124*n=963+18\left(n-1\right)$

106n = 945

 $\therefore n=\frac{945}{106}=8.91\approx 9$