Daily use candles (paraffin wax) contain

When a certain alkane is mixed with chlorine and irradiated with ultraviolet light,only one monochloroalkane is formed. This alkane is likely to be:

Which of the following will give two isomeric monochloro derivatives?

Which isomer of a hydrocarbon with a molecular mass of $72 \ u$ gives only one mono-substituted alkyl halide upon reaction with halogen?

An alkane $(Y)$ requires $8$ moles of oxygen for complete combustion and on chlorination with $Cl_2/h\nu$, $(Y)$ gives only one monochlorinated product $(Z)$. The total number of primary carbon atoms in $(Y)$ is . . . . . . .

The condition for the maximum yield of $C_2H_5Cl$ is: