Widespread deaths due to liquor poisoning occur due to

The compound which gives the most stable carbocation on dehydration is:

The major product obtained by the dehydration of the given alcohol is:

Which of the following alcohols cannot be prepared by the reaction of an acid chloride with an excess of a Grignard reagent followed by acidification?

An alcohol $X$ $(C_4H_{10}O)$ reacts with concentrated $HCl$ at room temperature to give $Y$ $(C_4H_9Cl)$. Reaction of $X$ with copper at $573 \ K$ gives $Z$. What is $Z$?

$CH_3 CH_2 OH \underset{\text{step-}1}{\stackrel{Cl_2}{\longrightarrow}} CH_3 CHO$ $\underset{\text{step-}2}{\stackrel{3 Cl_2}{\longrightarrow}} Cl_3 CCHO$
In the above reactions,the role of $Cl_2$ in step-$1$ and step-$2$ respectively is: