Total number of possible stereoisomers of dimethylcyclopentane is $....$

Which of the following contains a plane of symmetry?

Isomers have the same ...........

In the projection formula $[A]$,two groups ($Br$ and $CH_3$) at the chiral center are interchanged to obtain formula $[B]$. When two groups ($C_2H_5$ and $Cl$) of $[A]$ are interchanged,the projection formula $[C]$ is obtained. Which of the following statements is $NOT$ correct for $[A]$,$[B]$,and $[C]$?

The total number of acyclic isomers including the stereoisomers with the molecular formula $C_4H_7Cl$ is:

Which of the following statements is incorrect?