The composition of thermite mixture is (a) iron (III) oxide and aluminium powder in the ratio \(1: 3\) (b) aluminium powder and iron (III) oxide in the ratio \(1: 3\) (c) aluminium powder and barium peroxide in the ratio \(1: 3\) (d) barium peroxide and aluminium in the ratio \(1: 3\)

Thermite mixture is composed of a metal oxide and a reducing agent. In this case, the metal oxide is iron (III) oxide (Fe2O3) and the reducing agent is aluminium powder (Al).

We have identified that thermite mixture is composed of iron (III) oxide and aluminium powder. So, we can eliminate options (c) and (d) since they contain barium peroxide, which is not a component of thermite mixture.

To find the correct ratio of iron (III) oxide and aluminium powder, we need to focus on the remaining options: (a) and (b). The stoichiometry of the thermite reaction is given by: $$ 2\, \text{Al} + \text{Fe}_2\text{O}_3 \longrightarrow 2\, \text{Fe} + \text{Al}_2\text{O}_3 $$ Now, we need to find the mass ratio for the reaction: 1. Find the molar masses of iron (III) oxide (Fe2O3) and aluminium (Al): - For Fe2O3: \((2 * 55.85) + (3 * 16.00) = 159.70\) g/mol - For Al: \(26.98\) g/mol 2. Calculate the mass ratio of iron (III) oxide to aluminium: - From the stoichiometry of the reaction: \(\frac{1\, \text{mol}\, \text{Fe}_2\text{O}_3}{2\, \text{mol}\, \text{Al}}\) - Mass ratio: \(\frac{159.70\, \text{g}\, \text{Fe}_2\text{O}_3}{(2 * 26.98)\, \text{g}\, \text{Al}} = \frac{159.70}{53.96} \approx 2.96\) Therefore, the correct ratio of iron (III) oxide and aluminium powder is approximately \(3:1\).

The correct option is (b) aluminium powder and iron (III) oxide in the ratio \(1:3\).