Which of the following compounds is used as the starting material for the preparation of potassium dichromate ?

Options

A. `K_(2)SO_(4).Cr(SO_(4))_(3).24H_(2)O` (chrome alum)
B. `PbCrO_(4)` (Chrome yellow)
C. `FeCr_(2)O_(4)`(chromite)
D. `PbCrO_(4).PbO`(chrome red)

Answer

C

Explanation

`4FeO.Cr_(2)O_(3)("chromite ore")+8Na_(2)CO_(3)+7O_(2)undersetto("Roasting in air") 8Na_(2)CrO_(4)+2Fe_(2)O_(3)+8CO_(2)`
`2Na_(2)CrO_(4)+H_(2)SO_(4) to Na_(2)Cr_(2)O_(7)+NaSO_(4)+H_(2)O,Na_(2)Cr_(2)O_(7)+2KCltoK_(2)Cr_(2)O_(7)toK_(2)Cr_(2)O_(7)+2NaCl`