The yellow colour solution of `Na_(2)CrO_(4)` changes to orange red on passing `CO_(2)` gas due to the formation of :-

Answer

C

Explanation

`CO_2+H_2OtoH_2OhArr 2H^(+)+CO_3^(2-),2CrO_4^(2-)+2H^(+)hArr Cr_2O_7^(2-)("Orange red")+H_2O`