Short answer question $($Unit $5)$ Stereochemistry

Differentiate between Stereoselective and stereospecific reaction.

Write the principle of the polarimetry instrument.

Differentiate between enantiomer and diastereomers with the help of examples.

Define the following terms:

A$)$ Racemic mixture

B$)$ Meso compounds

Why the addition of $\frac{H_2}{Pt}$ to cis $2-$butene gives meso products whereas addition of $B\frac{r_2}{C}{H}_{2}C{l}_2$ to the cis $2-$butene gives racemic mixture?

What is the condition of any compound to be optically active?

Differentiate between erythro and threo isomers. What are the condition in addition reaction of alkenes to get erythro products.

Hint:

Cis$-$ alkene Syn addition $(H2$ addition$)$ we get erythro enantiomers products Transalkene antiaddition $(Br2$ addition$)$ we get threo enantiomers products