The conformations of $n$-butane, commonly known as eclipsed, gauche, and anti-conformations, can be interconverted by:

Most stable conformation of butane$-1,4-$dioic acid is

In the Newman projection for $2,2$-dimethylbutane,what can $X$ and $Y$ respectively be?
$A$. $H$ and $H$
$B$. $H$ and $C_2H_5$
$C$. $C_2H_5$ and $H$
$D$. $CH_3$ and $CH_3$

Which one of the following conformations of cyclohexane is chiral?

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 of the following conformations of butane is the least stable?