$CH_2 = CH_2$ $\xrightarrow{HBr} X$ $\xrightarrow{\text{Hydrolysis}} Y$ $\xrightarrow[I_2 \text{ excess}]{Na_2CO_3} Z$. What is $Z$ in the given reaction?

Which of the following compounds reacts immediately with Lucas reagent?

Distinction between primary,secondary and tertiary alcohol is done by

Ethylene may be obtained by dehydration of which of the following with concentrated $H_2SO_4$ at $160-170 \ ^oC$?

$A$ compound with the formula $C_4H_{10}O$ reacts with sodium and upon oxidation gives a carbonyl compound that does not reduce Tollen's reagent. What is the original substance?

$A$ toxic compound $A$ when reacted with $NaCN$ in aqueous acidic medium yields an edible cooking component and food preservative $B$. $B$ is converted to $C$ by diborane and can be used as an additive to petrol to reduce emission. $C$ upon reaction with oleum at $140^{\circ} C$ yields an inhalable anesthetic $D$. Identify $A, B, C$ and $D$,respectively.