An inorganic Compound `(A)` has garnet red prismatic crystals. `(A)` is modertely soluble in water and dissolved in cold concentrated `H_(2)SO_(4)` to yield red crystal `(B)` . In presence of dilute `H_(2)SO_(4)` it converts a pungent gas `(C )` into yellow turbidity `(D)` and converts a Suffocating gas `(E)` into a green solution `(F)`. the gas `(C )` and `(E)` also combine to produced the yellow turbidity `(D)` . With `KI` and starch in presence of dilute. `H_(2)SO_(4)` (A)` and concentrated `H_(2)SO_(4)` Mixture used as a cleansing agent for glassware in the laboratory . identify `(A)` and explain the reactions.

Explanation

As compound (A) has garnet red prismatic crystals which with cold conc.` H_(2)SO_(4)` gives red crystals and a suffocating gas `(SO_(2))` turn its solution in water in to green coloured solution , therefore compound (A) may be `K_(2)Cr_(2)O_(7) . K_(2)Cr_(2)O_(7)+4H_(2)SO_(4)+3H_(2)StoKHSO_(4)+2CrO_(3)("red crystals")+H_(2)O`
`K_(2)Cr_(2)O_(7)+4H_(2)SO_(4)+3H_(2)StoK_(2)SO_(4)+Cr(SO_(4))_(3)+7H_(2)O+3Sdownarrow(yellow)`
`K_(2)Cr_(2)O_(7)+4H_(2)SO_(4)+3H_(2)StoCr_(2)(SO_4)_(3)("Green solution")+K_(2)SO_(4)+H_(2)O`
`K_(2)Cr_(2)O_(7)+7H_(2)SO_(4)+6KIto4K_(2)SO_(4)+Cr_(2)(SO_4)_(3)+7H_(2)O+3I_(2)`
`I_(2)`+Starch to Blue colour