An alkane ( Y ) requires 8 moles of oxygen for complete combustion and on chlorination with Cl_2 / h ν,( Y ) gives only one monochlorinated product…

An alkane $\displaystyle (\mathrm{Y})$ requires $\displaystyle 8$ moles of oxygen for complete combustion and on chlorination with $\displaystyle \mathrm{Cl}_2 / \mathrm{h} \nu,(\mathrm{Y})$ gives only one monochlorinated product (Z). The total number of primary carbon atoms in $\displaystyle (Y)$ is $\displaystyle \_\_\_\_$.