In the following reaction, $'A'$ is:
$C_2H_5MgBr + \text{oxirane} \xrightarrow{H_2O} A$

What is the major organic product of the following sequence of reactions?
$(CH_3)_2CHCH_2OH$ $\xrightarrow{PBr_3}$ $\xrightarrow{Mg}$ $\xrightarrow{C_2H_4O}$ $\xrightarrow{H_3O^+} ?$

Explain the methods of preparing alcohols from carbonyl compounds using Grignard reagents.

Show how will you synthesize:
$(i)$ $1-$phenylethanol from a suitable alkene.
$(ii)$ cyclohexylmethanol using an alkyl halide by an $S_{N}2$ reaction.
$(iii)$ pentan$-1-$ol using a suitable alkyl halide?

$2-$methyl$-2-$butene on hydration gives an alcohol $X$. An isomer of $X$ could be prepared from which of the following?

What are $X$ and $Y$ in the following reactions?
$CH_2O \xrightarrow[(ii) H_3O^+]{(i) X} CH_3(CH_2)_2CH_2OH$
$Y \xrightarrow[(ii) H_3O^+]{(i) C_2H_5MgBr} CH_3CH_2C(CH_3)_2OH$