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

In the following structures,which one is having a staggered conformation with the maximum dihedral angle?

On Pluto,where everything is frozen,astronauts discovered two forms of butane: gauche and anti. Assuming that there are no rotations around single bonds,which statement about the two forms is correct?

The Newman projection representation of $CH_3-CH_2-CH(CH_3)-CH_2-CH_3$ about the $C_2-C_3$ bond is shown. Then $X$ and $Y$ are respectively:

Isomers that can be interconverted by rotation around a single bond are called....

If the $C_2$ carbon in the given Newman projection is rotated by $120^{\circ}$ in the anticlockwise direction,what will be the resulting conformation of the $C_2-C_3$ bond?