Methanol and ethanol are distinguished by the

What are $X$ and $Y$ in the following reactions?

The main product of the following reaction is:
$C_6H_5-CH_2-CH(OH)-CH(CH_3)_2 \xrightarrow{conc. H_2SO_4} ?$

Which one of the following will most readily dehydrate in acidic condition?

Ethylene glycol,on oxidation with periodic acid $(HIO_4)$,gives:

Which combination of alkyl bromide and epoxide can be used to prepare the following product by addition of the Grignard reagent derived from the alkyl bromide to the epoxide?