The first step in producing pure lead from galena $(PbS)$ is as follows: $ 2{PbS}(s) + 3{O}_2(g) \longrightarrow 2{PbO}(s) + 2{SO}_2(g) $.
All of the following are true concerning this reaction except:
200 cc of $x \times 10^{-3}$ M potassium dichromate is required to oxidise 750 cc of 0.6 M Mohr's salt solution in acidic medium. Here x = ______ .
