In compound $(X)$, hyperconjugation is present and in $(Y)$, resonance effect is present. What are $X$ and $Y$, respectively?

An alcohol $X\left(\mathrm{C}_4 \mathrm{H}_{10} \mathrm{O}\right)$ on dehydration gave alkene $\left(\mathrm{C}_4 \mathrm{H}_8\right)$ as major product, which on bromination followed by treatment with $Y$ gave alkyne $\mathrm{C}_4 \mathrm{H}_6$. Alkyne $\mathrm{C}_4 \mathrm{H}_6$, does not react with sodium metal. What are $X$ and $Y$ ?

An element occurs in the body centred cubic structure with edge length of 288 pm . The density of the element is $7.2 \mathrm{~g} \mathrm{~cm}^{-3}$. The number of atoms present in 208 g of the element is nearly

An aqueous solution containing 0.2 g of a non volatile solute ' $A$ ' in 21.5 g of water freezes at 272.814 K . If the freezing point of water is 273.16 K , the molar mass (in $\mathrm{g} \mathrm{mol}^{-1}$ ) of solute $A$ is $\left[\mathrm{K}_f\left(\mathrm{H}_2 \mathrm{O}\right)=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right]$