Let the atomic weight of alkali metal A be x. When it reacts with water, it forms a compound B having molecular mass 40. Let the reaction be
According to the question,
x + 16 + 1 = 40 (Given)
x = 40-17 = 23
It is the atomic weight of Na (sodium).
Therefore, the alkali metal (A) is Na and the reaction is
So, compound B is sodium hydroxide (NaOH).
Sodium hydroxide reacts with aluminium oxide (Al2O3) to give sodium aluminate (NaAlO2). Thus, C is sodium aluminate (NaAlO2). The reaction involved is Al2O3+