Which of the following pairs of compounds are enantiomers?

Consider the sets $I$,$II$,and $III$. Identify the set$(s)$ which is (are) correctly matched.
$I$. $\text{Staggered ethane} > \text{eclipsed ethane} \dots \dots \dots \text{torsional strain}$.
$II$. $2, 2-\text{Dimethylbutane} > 2-\text{methylpentane} \dots \dots \dots \text{boiling point}$.
$III$. $cis-\text{but}-2-\text{ene} > trans-\text{but}-2-\text{ene} \dots \dots \dots \text{dipole moment}$.

Identify the conformer of $2$-methylpentane.

Which of the following compounds does not undergo base-catalyzed exchange in $D_2O$ even though it has an $\alpha$-hydrogen?

Acetone and acetaldehyde are

Match the terms mentioned in Column-$I$ with the terms in Column-$II$.

Column-$I$	Column-$II$
$(A)$ Carbocation	$(1)$ Cyclohexane and $1$-hexene
$(B)$ Nucleophile	$(2)$ Conjugation of electrons of $C-H$ $\sigma$-bond with empty $p$-orbital present at adjacent positively charged carbon
$(C)$ Hyperconjugation	$(3)$ $sp^{2}$ hybridised carbon with empty $p$-orbital
$(D)$ Isomers	$(4)$ Ethyne
$(E)$ $sp$ hybridisation	$(5)$ Species that can receive a pair of electrons
$(F)$ Electrophile	$(6)$ Species that can supply a pair of electrons