An alkyl bromide reacts with sodium ethoxide and ethanol to give only one alkene. Hydrogenation of this alkene yields $2-$methylbutane. What is the alkyl halide?

What is the number of possible enantiomeric pairs formed during the monochlorination of isopentane?

Prolonged exposure of chloroform in humans may cause damage to the liver. It is due to the formation of the following compound.

Monochlorination of toluene in the presence of sunlight followed by hydrolysis gives:

$A$ solution of $(-)-1-$chloro$-1-$phenylethane in toluene racemises slowly in the presence of a small amount of $SbCl_5$,due to the formation of:

Compound $A$ with molecular formula $C_4H_9Br$ is treated with aqueous $KOH$ solution. The rate of this reaction depends upon the concentration of compound $A$ only. When another optically active isomer $B$ of this compound was treated with aqueous $KOH$ solution,the rate of reaction was found to be dependent on the concentration of both the compound and $KOH$.
$(i)$ Write down the structural formula of both compounds $A$ and $B$.
$(ii)$ Out of these two compounds,which one will be converted to the product with inverted configuration?