$$ \mathrm{RO}-\mathrm{CH}_2-\mathrm{C} \equiv \mathrm{CH} \xrightarrow{\mathrm{X}} \xrightarrow{\mathrm{Y}} \mathrm{RO}^{-} \mathrm{CH}_2-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}_2 \mathrm{CH}_2-\mathrm{Br} $$

To carry out the above conversion X and Y are respectively

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

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

The decreasing order of reactivity of the following alkenes towards $$\mathrm{HBr}$$ addition is