With respect to the conformers of ethane, which of the following statements is true?

The most stable conformation of n-butane among the following is:

1.		2.
3.		4.

Dihedral angle in staggered form of ethane is:

1. $0°$

2. $120°$

3. $60°$

4. $180°$

R and S enantiomers differ in:

1. Chemical properties

2. Solubility in achiral solvent

3. Rotation of plane polarised light.

4. Dipole moment