Vinyl chloride reacts with $HCl$ to form

Which one of the following has the highest boiling point?

The compound added to prevent chloroform from forming phosgene gas is

In solvolysis of $1,2$-dimethylpropyl $p$-toluenesulfonate in acetic acid at $75^\circ C$,(alkene + substitution products) will be formed by which mechanism?

Which of the following reactions is an example of an $S_{N}2$ reaction?

Dehydrohalogenation of an alkyl halide is a/an