Identify all the possible monochloro structural isomers expected to be formed on free radical monochlorination of
$(C{H}_3{)}_{2}CHC{H}_{2}C{H}_3.$

Structural isomers

These are isomers with same molecular formula but differ in properties due to different structures.

Possible products after monochlorination

In the given molecule, there are four different types of hydrogen atoms which are denoted by $a,b,c\text{and}d$ as shown below:


Replacement of these hydrogen atoms will given the four different types of products after mono chlorination which are
shown below: