Which among the following has the lowest boiling point?

Identify $Z$ in the following series:
$CH_2=CH_2$ $\xrightarrow{HBr} X$ $\xrightarrow{Hydrolysis} Y$ $\xrightarrow[I_2 \ \text{excess}]{Na_2CO_3} Z$

What is the order of reactivity of the following alcohols with halogen acids?
$(1) \ CH_3CH_2CH_2OH$
$(2) \ CH_3CH_2CH(CH_3)OH$
$(3) \ CH_3CH_2C(CH_3)_2OH$

Which of the following alcohols undergoes dehydration most easily with concentrated $H_2SO_4$?

The alcohol that produces turbidity immediately with $ZnCl_2 +$ conc. $HCl$ at room temperature is:

When a Grignard reagent reacts with $(B)$,product $(D)$ is obtained. Reactant $(A)$ of the above reaction is:
$(A)$ $\xrightarrow{PBr_3} (C)$ $\xrightarrow{Mg, \text{ether}} \text{Grignard reagent}$
$(A) \xrightarrow{Na_2Cr_2O_7, H_2SO_4} (B)$
$\text{Grignard reagent} + (B) \to (D) \xrightarrow{H_3O^\oplus} (3,4-\text{dimethylhexan-3-ol})$