The Newman projection shown below is known as the:

The structures shown below represent .......

Arrange the following molecules in the correct order of stability (decreasing order):

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:

Arrange the following conformational isomers of $n$-butane in order of their increasing potential energy:

Which statement is true for cyclohexane?