1.0 g of Mg is burnt in a closed vessel which contains 0.5 g of `O_2`.
(i) Which reactant is left in excess?
(ii) Find the weight of excess reactant.
(iii) How many millilitres of `0.5 N H_2 SO_4` will dissolve the residue in the vessel?

Explanation

To solve the problem step by step, we will follow the outlined parts of the question:

### Step 1: Write the balanced chemical equation
The reaction between magnesium (Mg) and oxygen (O2) can be represented as:
\[ 2 \text{Mg} + \text{O}_2 \rightarrow 2 \text{MgO} \]

...