When ethanol is treated with sulphuric acid at $413 \ K$,the reaction involved in it is:

Identify the major product formed when $2-$Methylhexan$-3-$ol is heated with concentrated sulphuric acid.

In the following reaction sequence,the compound $I$ is:
$I (C_3H_6Cl_2)$ $\xrightarrow{KOH_{(aq)}} II$ $\xrightarrow{(i) CH_3MgBr, (ii) H_2O/H^{+}} III$ $\xrightarrow{Anhy. ZnCl_2 + Conc. HCl}$ gives turbidity immediately.

The compound on dehydrogenation gives a ketone. The original compound is

Compound $A$ and $C$ in the following reaction are
$CH_3CHO$ $\xrightarrow[(i) \, CH_3MgBr]{(ii) \, H_2O} A$ $\xrightarrow{H_2SO_4, \Delta} B$ $\xrightarrow{\text{Hydroboration-Oxidation}} C$

Which of the following compounds reacts immediately with Lucas reagent?