Question

 When a metal X is treated with cold water, it gives a basic salt Y With molecular formula XOH (molecular mass =40) and liberates a gas Z which easily catches fire. Identify X , Y and Z and also write the reaction involved. 

Answer 1

Molecular mass of base Y (XOH) = 40
Atomic mass of X = 40 - (16 + 1) = 23
The metal X is sodium (Na). The salt Y is NaOH and liberated gas Z is hydrogen.
`underset(("X"))(2Na(s)) + 2H_(2)O(aq) rarrunderset(("Y"))(2NaOH)(aq) + H_(2)(g)`