XeF₆ on partial hydrolysis with water produces a compound ‘X’. The same compound ‘X’ is formed when XeF₆ reacts with silica. The compound ‘X’ is :

The number of P−OH bonds and the oxidation state of phosphorus atom in pyrophosphoric acid (H₄P₂O₇) respectively are :

The correct sequence of decreasing number of $$\pi $$-bonds in the structures of H₂SO₃, H₂SO₄ and H₂S₂O₇ is :

A metal ‘M’ reacts with nitrogen gas to afford ‘M₃N’. ‘M₃N’ on heating at high temperature gives back ‘M’ and on reaction with water produces a gas ‘B’. Gas ‘B’ reacts with aqueous solution of CuSO₄ to form a deep blue compound. ‘M’ and ‘B’ respectively are :