Which of the following compounds is used as an antifreeze agent in automobile radiators?

The major product of the following reaction is:

Identify product '$B$' in the following series of reactions: $2-methylpropan-2-ol \xrightarrow{20\% H_2SO_4, 363 K} A \xrightarrow{H_2O, \Delta, Conc. H_2SO_4} B$

$CH_3CH_2CH(OH)CH(CH_3)_2 + CH_3COCl \xrightarrow{\text{base}} CH_3CH_2CH(OCOCH_3)CH(CH_3)_2 + HCl$
In the above reaction,if the reactant alcohol is a pure $R$-isomer,the product would:

Iodoform can be prepared from all,except

For the given reaction,if the final product is a mixture of $C_4H_8Br_2$ isomers,what is the value of $X$ (the number of alkenes formed in the mixture)?