A white sodium salt dissolves readily in water to give a solution which is neutral to litmus. When silver nitrate solution is added to the aformentioned solution, a white precipitate is obtained which does not dissolve in dil. nitric acid. The anion is :

Xenon hexafluoride on partial hydrolysis produces compounds 'X' and 'Y' . Compounds 'X' and 'Y' and the oxidation state of Xe are respectively :

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

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