Chrome iron ore (x) was heated with dry `Na_(2)CO_(3)` in the presence of quick lime and air in a furnace. The mixture was extracted with water and filtered. The filtrate was yellow(A) which on adding conc. `H_(2)SO_(4)` turned to orange red. The solution was evaporated and cooled. The crystals of B were obtained. To the crystals in aqueous solution, `NH_(4)Cl` was added. On fractional crystallization, orange red crystals (C ) is formed.
`underset(Delta)overset("Furnace")(rarr)A+CO_(2)uarr+Fe_(2)O_(3)`. The 'y' in the stoichiometrically balanced equation is

Options

A. 3
B. 7
C. 6
D. 2

Answer

B

Explanation

`2Fe(CrO_(2))_(2)+4Na_(2)CO_(3)+7O_(2)rarrFe_(2)O_(3)+4Na_(2)CrO_(4)+8CO_(2)`