A magnesium ribbon is burnt in oxygen to give a white compound X accompanied by emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it continues to burn and forms a compound Y.
(a) Write the chemical formulae of X and Y.
(b) Write a balanced chemical equation, when X is dissolved in water.

Explanation

When magnesium ribbon burns in air, it forms magnesium oxide, a white compound accompanied by emission of light. `2Mg + O_(2) to 2MgO`
When the burning ribbon is placed in an atmosphere of nitrogen, it continues to burn and forms a compound magnesium nitride.
`3Mg + N_(2) to Mg_(3)N_(2)`
(a) Thus, X is MgO and Y is `Mg_(3)N_(2)`
(b) When magnesium oxide is dissolved in water, it forms magnesium hydroxide.
`MgO + H_(2)O to Mg(OH)_(2)`