While naming the compound, first identify the longest Carbon chain - Propane

Secondly, identify the substituent groups, i.e the functional groups - There are two substituents present, Chloro (on Carbon- 1) and Methyl (On carbon - 2)

Alphabetically, Chloro comes before methyl, hence the naming will take the form 1-chloro, 2-methyl

Finally, bring all the names together, starting with the substituents, i.e 1-chloro,2-methyl propane