Question

Among the isomeric alkanes of molecular formula C₅H_12, identify the one that on
photochemical chlorination yields (i) A single monochloride.
(ii) Three isomeric monochlorides.
(iii) Four isomeric monochlorides.

Answer 1

(i) To have a single monochloride, there should be only one type of H-atom in the isomer of the alkane of the molecular formula C₅H₁₂. This is because, replacement of any H-atom leads to the formation of the same product. The isomer is neopentane.

(ii) To have three isomeric monochlorides, the isomer of the alkane of the molecular formula C₅H₁₂ should contain three different types of H-atoms. Therefore, the isomer is n-pentane. It can be observed that there are three types of H
atoms labelled as a, b and c in n-pentane.

(iii) To have four isomeric monochlorides, the isomer of the alkane of the molecular
formula C₅H₁₂ should contain four different types of H-atoms. Therefore, the isomer is 2methylbutane. It can be observed that there are four types of H-atoms labelled as a, b,
c, and d in 2-methylbutane.