$\mathrm{NaCl}$ reacts with conc. $\mathrm{H}_2 \mathrm{SO}_4$ and $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ to give reddish fumes (B), which react with $\mathrm{NaOH}$ to give yellow solution (C). (B) and (C) respectively are ;