The general formula of an alkane is CnH2n+2.
The balanced chemical equation for the complete combustion of an alkane is:
CnH2n+2+(23n+1)O2→nCO2+(n+1)H2O
Given that 8 moles of oxygen are required for complete combustion:
23n+1=8
3n+1=16
n=5
The molecular formula of the alkane (Y) is C5H12.
Since (Y) yields only one monochlorinated product (Z) upon reaction with Cl2/hν, all the hydrogen atoms in the alkane must be equivalent.
Among the isomers of C5H12 (n-pentane, isopentane, and neopentane), only 2,2-dimethylpropane (neopentane) has all equivalent hydrogen atoms.
The structure of neopentane is C(CH3)4.
In this structure, the central carbon is quaternary, and the four surrounding methyl carbons are primary carbon atoms.
Therefore, the total number of primary carbon atoms in (Y) is 4.
Answer: 4