A 200 g sample of refined sugar contains 1.5 g of impurities. Calculate the purity percentage of the sugar.

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

Answer

99.25%

The correct answer is $99.25%$ — Multiply by 100 to get $0.9925 \times 100 = 99.25%$ .

Step-by-step solution

Use the purity formula: $\frac{total mass - impurity mass}{total mass} \times 100$ .
Substitute the values: $\frac{200 - 1.5}{200} \times 100$ .
Compute the numerator: $200 - 1.5 = 198.5$ .
Divide by 200: $198.5 \div 200 = 0.9925$ .
Multiply by 100 to get $0.9925 \times 100 = 99.25%$ .

Common mistake: Subtracting purity from total instead of impurity

Concept tested: Purity calculation with impurity mass