A silvery white metal X reacts with water at room temperature to produce a water soluble compound Y and a colourless gas Z. The reactions is highly exothermic and the Z catches fire immediately during the reaction. The solution of Y in water on reacting with stoichiometric amount of dilute solution of hydrochloric acid gives a solution of pH = 7.0. The compounds X, Y and Z respectively are:
Na, NaOH and H2
Na+H2O→NaOH+H2+Heat(x)(y)(z)NaOH+HCl→Nacl+H2O(pH=7)(neutral)