Which compound is soluble in water?

In the following sequence of reaction,$Z$ $\xrightarrow{PCl_5} X$ $\xrightarrow[\Delta]{\text{Alc. KOH}} Y$ $\xrightarrow{H_2O/H^{+}} Z$ (Major),$Z$ is:

Which of the following alcohols will undergo dehydration most easily?

Give the structures of the products you would expect when each of the following alcohols reacts with $(a)$ $HCl - ZnCl_{2}$,$(b)$ $HBr$,and $(c)$ $SOCl_{2}$: $(i)$ $Butan-1-ol$,$(ii)$ $2-Methylbutan-2-ol$.

$CH_3-CH(OH)-CH_3$ $\xrightarrow{PBr_3} X$ $\xrightarrow{Mg/\text{ether}} Y$ $\xrightarrow{H_2O/H^+} \text{The final product is}$

Lead pipes are corroded quickly by