What are $X, Y, Z$ in the following reaction sequence respectively?

A Grignard reagent $(X)$ on reaction with carbonyl compound $(Y)$ followed by hydrolysis gave $Z$. $Z$ reacts with conc. HCI at room temperature, $X$ and $Y$ respectively are

An organic compound $(X)$ has an empirical formula $\mathrm{C}_4 \mathrm{H}_8 \mathrm{O}$. This gives a pale yellow precipitate with iodine in NaOH solution. What is $X$ ?

Which of the following sets of reagents convert toluene to benzaldehyde?

A. $\mathrm{Cl}_2 \mid h v ; \mathrm{H}_2 \mathrm{O}, \Delta$

B. $\mathrm{KMnO}_4 \mid \mathrm{OH}^{-} ; \mathrm{H}^{+}$

C. $\mathrm{Cl}_2 \mid \mathrm{Fe} ; \mathrm{H}_2 \mathrm{O}$

D. $\mathrm{CrO}_2 \mathrm{Cl}_{21} \mid \mathrm{CS}_2 ; \mathrm{H}_3 \mathrm{O}^{+}$