When alcohol vapor is passed over heated reduced copper,the alcohol is converted into an alkene. Which type of alcohol is it?

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 reagents is used to convert ethyl alcohol into ethyl chloride?

The correct statement about the product of the following reaction is
$CH_3-CHO \xrightarrow[(ii) H_2O]{(i) C_2H_5MgBr} \text{product}$

In the following sequence of reactions,the compound $C$ formed will be:
$CH_3-CH(NH_2)-CH_3$ $\xrightarrow{HNO_2} A$ $\xrightarrow{\text{Oxidation}} B$ $\xrightarrow[(ii) H^+/H_2O]{(i) CH_3MgI} C$

In the given reaction,$[X]$ is: