Correct Answer - A
By the action of concentrated sulphuric acid, sodium chromate gets converted into sodium dichromate in the manufacture of potassium dichromate.
Various steps involeved are :
Step I Concerntration of the chromit ore by wilfley method.
Step II Conversion of the concentrate chromite ore into `Na_(2)CrO_(4)`. Concentrated chromit ore is fused with molten `Na_(2)CO_(3)` in the presence of air when `Na_(2)CrO_(4) and Fe_(2)O_(3)` are formed.
Step III Conversion of `Na_(2)CrO_(4)` into `Na_(2)Cr_(2)O_(7)`
Aqueous solution of `Na_(2)CrO_(4)` is acidified to obtain `Na_(2)Cr_(2)O_(7)`.
`Na_(2)CrO_(4)+H_(2)underset("Dil.")(SO_(4))rarrNa_(2)Cr_(2)O_(7)+H_(2)O`