An alkali metal 'A' gives a compound B (molecular mass = 56) on reacting with water. The compound 'B' gives a soluble compound 'C' on treatment with aluminium oxide. Identify A, B and C and give the reactions involved.

Explanation

The alkali metal 'A' is potassium (K) and on reacting with water, it forms a compound 'B' which is potassium hydroxide. This upon reacting with alumnium oxide `(Al_(2)O_(3))` forms potassium metaluminate 'C'.
`underset(("A"))(2K(s)) + 2H_(2)O(aq) rarr underset(("B"))(2KOH(aq)) + H_(2)(g)`
`underset(("B"))(2KOH)(aq) + Al_(2)O_(3)(s) rarr underset(("C"))(2KAlO_(2))(aq) + H_(2)O(aq)`