In the energy diagram, dihedral angle of the conformations of ethane, the staggered forms are found at:

Incorrect statement about the compounds $\mathrm{I}, \mathrm{II}$ is

$\left(\mathrm{I}\right)$ 

$\left(\mathrm{II}\right)$ 

$\left(\mathrm{III}\right)$

The configuration at $\mathrm{C}-2$ and $\mathrm{C}-5$ in the following compound, respectively, are:

The Newman projection of

is known as the