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

To solve the problem step by step, we will identify the compounds formed when magnesium is burnt in oxygen and nitrogen, and then write the balanced chemical equation for the reaction of compound X with water.

### Step 1: Identify the compound X formed when magnesium burns in oxygen.
- When magnesium (Mg) burns in oxygen (O2), it reacts to form magnesium oxide (MgO).
- This reaction is exothermic, meaning it releases light and heat.

**Chemical formula for X:**
\[ \text{X} = \text{MgO} \]
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