Which energy diagram best represents the given reaction?

How many isomers (cyclic and acyclic) are possible for a compound with molecular formula $C_3H_6O$?

The correct energy profile for amine inversion and the hybridization of nitrogen in the transition state is:

Which of the following are meso compounds?

Examine the following three pairs of possible isomers. Now state whether the pairs represent identical compounds or different isomers.

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