Question

A silvery-white metal X taken in the form of ribbon, when ignited, burns in air with a dazzling white flame to form a white powder Y. When water is added to powder Y, it dissolves partially to form another substance Z.
(a) What could metal X be?
(b) What is powder Y?
(c) With which substance metal X combines to form powder Y?
(d) What is substance Z? Name one domestic use of substance Z.
(e) Write a balanced chemical equation of the reaction which takes place when metal X burns in air to form powder Y.

Answer 1

(a) Metal X could be magnesium metal.

(b) Powder Y is magnesium oxide (MgO).

(c) Magnesium metal (X) combines with oxygen gas to form powdery magnesium oxide (Y).

(d) Substance Z is magnesium hydroxide [Mg(OH)₂]. Suspension of magnesium hydroxide (Z) is used as an antacid.

(e) 2Mg (s) + O₂ (g) → 2MgO (s)