In the following sequence of reactions,
$CH_3CH_2CH_2Br$ $\xrightarrow{KOH(alc.)}$ $(A)$ $\xrightarrow{HBr}$ $(B)$ $\xrightarrow{KOH(aq.)}$ $(C)$
The product $(C)$ is

$3 \ mol$ of ethanol reacts with $1 \ mol$ of phosphorus tribromide to give $3 \ mol$ of bromoethane and $1 \ mol$ of $X$. What is $X$?

What is formed when glycerol reacts with $HI$?

Identify the missing reagent/condition in the following reaction:
$CH_3CH_2OH \xrightarrow{?} CH_3CH_2-O-CH_2CH_3$

Which one has the highest boiling point?

Compound $A$ of molecular formula $C_4H_{10}O$ on treatment with Lucas reagent at room temperature gives compound $B$. When compound $B$ is heated with alcoholic $KOH$,it gives isobutene. Compound $A$ and $B$ are respectively: