Among the isomeric alkanes of molecular formula $C_{5}H_{12}$

Among the isomeric alkanes of molecular formula $C_{5}H_{12}$, identify the one that on photochemical chlorination yields .
(i) a single monochloride. (ii) three isomeric monochlorides. (iii) four isomeric monochlorides.

(i) A single monochloride (IV) can be produced only when all the hydrogen atoms are equivalent. This isomer must be symmetrical. Its structure is given by (I).

(ii) Isomer (II) has three groups of equivalent hydrogen atoms. Therefore, three isomeric monochlorides (V, VI and VII) are produced.