Which among the following is a benzylic halide?

Which of the following compounds is not chiral?

The number of possible monohalogen derivatives for the alkyl halide having molecular formula $C_4H_9X$ is

What is the molecular formula of allyl chloride?

Which of the following are vinyl chlorides?
$(a)$ $3\text{-chlorocyclohexene}$
$(b)$ $1\text{-chlorocyclohexene}$
$(c)$ $4\text{-chlorobut-1-ene}$
$(d)$ $1\text{-chloroethene}$
$(e)$ $3\text{-chlorobut-1-yne}$
$(f)$ $3\text{-chloro-2-methylpropene}$

The common name of $1-$chloro$-2,2-$dimethylpropane is