A 150 g sample of iron ore contains 120 g of pure iron and 30 g of impurities. Calculate the purity percentage of iron in the sample.

medium 2 marks Class 9 · Science · Is Matter Around Us Pure

Answer

80%

The correct answer is $80%$ — Multiply by 100 to get $0.8 \times 100 = 80%$ .

Step-by-step solution

Use the formula for purity: $\frac{mass of pure component}{total mass} \times 100$ .
Insert the given masses: $\frac{120}{150} \times 100$ .
Compute the fraction: $120 \div 150 = 0.8$ .
Multiply by 100 to get $0.8 \times 100 = 80%$ .

Common mistake: Using impurity mass instead of pure mass

Concept tested: Purity calculation