Which of the given statement(s) about $N$, $O$, $P$ and $Q$ with respect to $M$ is (are) correct?
$(A)$ $M$ and $N$ are non-mirror image stereoisomers
$(B)$ $M$ and $O$ are identical
$(C)$ $M$ and $P$ are enantiomers
$(D)$ $M$ and $Q$ are identical

Which of the following structures represents a meso-compound?

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 $[C]$?

Keto-enol tautomerism is found in

Determine the total number of stereoisomers possible for the following compound:
Structure: $A$ cyclopentene ring with a $-CH=CH-CH_2-CH_3$ group at position $1$ and a $-CH=CH_2$ group at position $2$.

Which type of isomerism is exhibited by the following compounds $I$ and $II$?
$(i)$ $CH_3CH=CHCH_3$
$(ii)$ $CH_3-CH(OH)-CH_2CH_3$