Identify the pairs of enantiomers and diastereomers from the following compounds $\mathrm{I}$, $\mathrm{II}$and $\mathrm{III}$:

Find the relationship between the given pairs.

($i$) Total number of fractions on fractional distillation of $\mathrm{I},$$II$ and $III$.
($ii$) Optical active compounds.
($iii$) Relation between $I$and $II$.
($iv$) Relation between $I$and $III$.

What does $D/L$ $\&$ $d/\mathcal{l}$ represent?

The total number of fractions ($n$) obtained in the following reaction is

Write the Newman projection formula of the following compounds:

(I) $\mathrm{Cl}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$ in its most polar form.

(II) $\mathrm{HO}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{OH}$ in its most stable form.

(III) $\mathrm{HOOC}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{COOH}$ in its least stable staggered form.