$C_2H_5OH$ can be differentiated from $CH_3OH$ by:

Identify $Z$ in the following reaction:
$CH_3CH_2OH$ $\xrightarrow{PBr_3} X$ $\xrightarrow{alc. KOH} Y$ $\xrightarrow[{(ii) H_2O, \text{heat}}]{{(i) H_2SO_4, \text{RT}}} Z$

$X + HCl$ $\xrightarrow[\text{Addition}]{\text{Anhy. } AlCl_3} C_2H_5Cl \xleftarrow[\text{Substitution}]{\text{Anhy. } ZnCl_2/HCl} Y$. The conversion of $Y$ to $X$ can be achieved by heating with .......... at .......... temperature.

$A$ on heating isomerizes to $B$. What is the structure of $B$?

Which of the following is a tertiary alcohol?

The product obtained by heating ethanol with concentrated $H_2SO_4$ at $165^{\circ}C - 170^{\circ}C$ is: