Reaction of ${\mathrm{Br}}_2$ with ${\mathrm{Na}}_2{\mathrm{CO}}_3$ in aqueous solution gives sodium bromide and sodium bromate with evolution of ${\mathrm{CO}}_2$ gas. The number of sodium bromide molecules involved in the balanced chemical equation is 

How many grams of potassium dichromate are required to oxidise $20.0 \mathrm{g}$ of ${\mathrm{Fe}}^{2+}$ in ${\mathrm{FeSO}}_4$ to ${\mathrm{Fe}}^{3+}$ if the reaction is carried out in an acidic medium ? (Molar mass of ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ and ${\mathrm{FeSO}}_4$ are $294$ and $152$ respectively)

Round off your answer to the nearest integer.