For which of the following molecules, Gauche form is more stable than Anti.

$\mathrm{i}.$ $\mathrm{M}\mathrm{e}-{\mathrm{C}\mathrm{H}}_2-{\mathrm{C}\mathrm{H}}_2-\mathrm{M}\mathrm{e}$   $\mathrm{i}\mathrm{i}.$ $\mathrm{H}\mathrm{O}-{\mathrm{C}\mathrm{H}}_2-{\mathrm{C}\mathrm{H}}_2-\mathrm{O}\mathrm{H}$
$\mathrm{i}\mathrm{i}\mathrm{i}.$ $\mathrm{H}\mathrm{O}-{\mathrm{C}\mathrm{H}}_2-{\mathrm{C}\mathrm{H}}_2-\mathrm{F}$

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

Which hydrogen in compound $\left(E\right)$ is easily replaceable during bromination reaction in presence of light ?

Isomers of hexane, based on their branching, can be divided into three distinct classes as shown in the figure.

The correct order of their boiling point is