NaBr , used to produce AgBr for use in photography can be self prepared as follows:
`Fe+Br_(2) to FeBr_(2) " "…(i) `
`FeBr_(2) + Br_(2) to Fe_(3) Br_(8)" "…(ii) `(not balanced)
`Fe_(3)Br_(8) + Na_(2)CO_(3) to NaBr+CO_(2) + Fe_(3)O_(4)" "...(iii)" "` (not balanced)
(At mass: Fe=56, Br=80)
Mass of iron required to produce `2.06xx10^(3)` kg NaBr
A. 420 gm
B. 420 kg
C. `4.2 xx 10^(5)` kg
D. `4.2 xx 10^(8)` gm
