What is the name of isobutyl alcohol according to carbinol system?

Which among the following is the method for the preparation of ethers?

The decreasing order of reactivity of following alcohols with halo acid is

(I) $\mathrm{CH}_3 \mathrm{OH}$

(II) $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH}$

(III)

(IV)

Identify the product ' $Z$ ' in the following series of reactions.

Ethanol $\xrightarrow[\Delta]{\mathrm{SOCl}_2} \mathrm{X} \xrightarrow[\text { Dryether }]{\mathrm{Mg}} \mathrm{Y} \xrightarrow{\mathrm{NH}_3} \mathrm{Z}$