Which of the following hydrocarbons reacts easily with $\mathrm{MeMgBr}$ to give methane?

Adiabatic free expansion of ideal gas must be

An optically active alkene having molecular formula $\mathrm{C}_8 \mathrm{H}_{16}$ gives acetone as one of the products on ozonolysis. The structure of the alkene is

$360 \mathrm{~cm}^3$ of a hydrocarbon diffuses in 30 minutes, while under the same conditions $360 \mathrm{~cm}^3$ of $\mathrm{SO}_2$ gas diffuses in one hour. The molecular formula of the hydrocarbon is