Compare the stabilities of the following two compounds $(A)$ and $(B)$:
$A$ : $cis-1$-ethyl-$3$-methylcyclohexane
$B$ : $trans-1$-ethyl-$3$-methylcyclohexane

Given below are two statements:
Statement $I$: There are several conformers for $n$-butane. Out of those conformers, the fully eclipsed conformer (dihedral angle $0^{\circ}$) is the least stable and the anti-staggered conformer (dihedral angle $180^{\circ}$) is the most stable.
Statement $II$: As the dihedral angle increases from $0^{\circ}$ to $60^{\circ}$, torsional strain decreases from the fully eclipsed conformer $(X)$ to the gauche conformer $(Y)$.
In the light of the above statements, choose the correct answer from the options given below:

Which conformation of cyclohexane is chiral?

In the following Newman projection of the skew conformation of ethane,the dihedral angle between $H'$ and $H''$ is $......^\circ$. (in $^\circ$)

The incorrect statement regarding conformations of ethane is:

Which is the most stable conformer of ethane-$1,2$-diol?