Arrange the following compounds in the increasing order of their boiling points:
$(a)$ $CH_3CH_2CH_2CH_2Br$
$(b)$ $(CH_3)_2CHCH_2Br$
$(c)$ $(CH_3)_3CBr$

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?

Which of the following compounds is optically inactive?

Which of the following compounds is most reactive towards $S_N1$ reaction?

Identify $A$ in the following reaction:

The product obtained from the reaction is: