Which one is the most stable conformer of $n$-butane?

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?

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

Which of the following conformations of $n$-butane is the most stable?

Among the following,the conformation that corresponds to the most stable conformation of meso-butane-$2,3$-diol is -

In the staggered conformation of $C_2H_6$,the dihedral angle between $H-C-C-H$ bonds is ....$^o$.