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

To a 25ml H₂O₂ solution, excess of acidified solution of potassium iodide was added. The iodine liberated required 20 ml of 0.3 N sodium thiosulphate solution. Calculate the volume strength of H₂O₂ solution.

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 reactions for the oxidation of hydrogen peroxide with potassium permanganate in acidic medium.