question_answer 85)

  An alkali metal A gives a compound B (molecular mass = 40) 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.

Answer:

                  Let the atomic weight of alkali metal A is x. When it reacts with water it forms a compound B having .molecular mass 40. Let, the reaction isAccording to question, molecular mass of compound                            (Given)                 it is the atomic weight of Na (sodium), Therefore, the alkali metal (A) is Na and the reaction is So, compound 6 is sodium hydroxide (NaOH) Sodium hydroxide reacts with aluminium oxide () to give sodium aluminate Thus, C is sodium aluminate The reaction involved is