Which of the following pairs are tautomers?

Which equilibrium is not rapid at room temperature?

The Fischer projection formula of the given structure is:

Find out the statements which are not true.
$A$. Resonating structure with more number of covalent bonds and lesser charge separation are more stable.
$B$. In electromeric effect, an unsaturated system shows $+E$ effect with nucleophile and $-E$ effect with electrophile.
$C$. Inductive effect is responsible for high melting point, boiling point and dipole moment of polar compounds.
$D$. The greater the number of alkyl groups attached to the doubly bonded carbon atoms, higher is the heat of hydrogenation.
$E$. Stability of carbanion increases with the increase in $s$-character of the carbon carrying the negative charge.
Choose the correct answer from the options given below.

Match List-$I$ with List-$II$.

List-$I$ Isomeric pairs	List-$II$ Type of isomers
$A$. Propanamine and $N$-Methylethanamine	$I$. Metamers
$B$. Hexan-$2$-one and Hexan-$3$-one	$II$. Positional isomers
$C$. Ethanamide and Hydroxyethanimine	$III$. Functional isomers
$D$. $o$-nitrophenol and $p$-nitrophenol	$IV$. Tautomers

Choose the correct answer from the options given below:

Most stable carbocation among the following is