Element A burns in nitrogen to give an ionic compound B. Compound B reacts with water to give C and D. A solution of C becomes 'milky' on bubbling carbon dioxide. Identify A, B, C and D.

Give reasons of the following:
The crystalline salts of alkaline earth metals contain more water of crystallisation than the corresponding alkali metal salts.

Arrange the following sulphates of Alkaline earth metals in order of decreasing thermal stability : BeSO₄, MgSO₄, CaSO₄, SrSO₄

Calculate the equilibrium constant for the reaction
Fe²⁺ + Ce⁴⁺ $$\leftrightharpoons$$ Fe³⁺ + Ce³⁺
(given $$E_{C{e^{4 + }}/C{e^{3 + }}}^o$$ = 1.44 V; $$E_{F{e^{3 + }}/F{e^{2 + }}}^o$$ = 0.68 V)