Which structural isomer of ${\mathrm{C}}_4{\mathrm{H}}_{10}\mathrm{O}$ cannot be dehydrogenated by copper at $573 \mathrm{K}$

What products are obtained when ethyl alcohol is heated with conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$ at

(i) $383 \mathrm{K}$

(ii) $413 \mathrm{K}$

(iii) $443 \mathrm{K}$

Arrange the following in the increasing order of acidity :

ethanol, ethanoic acid, $4$-nitrophenol, phenol.

Name one reagent which is used for the distinction of primary, secondary and tertiary alcohols.