1.
An inorganic white crystalline compound (P) has a rock salt structure. (P) on reaction with conc. H2SO4\text{H}_2\text{SO}_4 and MnO2\text{MnO}_2 evolves a pungent greenish-yellow gas (Q). (P) gives a white ppt. (R) with AgNO3\text{AgNO}_3. Compounds (P), (Q) and (R) are respectively: