Which of the following,upon treatment with $tert-BuONa$ followed by addition of bromine water,fails to decolourize the colour of bromine?

The product obtained from the reaction is:

Which of the following is the correct order of boiling points for alkyl halides?

When ethanol is reacted with $PCl_5$,it gives $A$,$POCl_3$,and $HCl$. Compound $A$ reacts with silver nitrite to give the major product $B$ and $AgCl$. What are $A$ and $B$ respectively?

Among the following,the most reactive towards alcoholic $KOH$ is:

The reaction of $t-$butyl bromide with sodium methoxide mainly gives .............