Among the following,the most stable isomer is

The correct statement$(s)$ concerning the structures $E, F$ and $G$ is (are):
$E$: $CH_3CH_2CH(CH_3)COCH_3$
$F$: $CH_3CH_2C(OH)=C(CH_3)_2$ (enol form)
$G$: $CH_3CH_2C(CH_3)=C(OH)CH_3$ (enol form)
$(A)$ $E, F$ and $G$ are resonance structures
$(B)$ $E, F$ and $E, G$ are tautomers
$(C)$ $F$ and $G$ are geometrical isomers
$(D)$ $F$ and $G$ are diastereomers

Which of the following is correct for the given compound?

Total number of acyclic and cyclic isomers possible for molecular formula $C_4H_6$ is

How many chiral carbons are there in Reserpine (an antipsychotic drug)?

Which of the following pairs are not diastereomers?