Question 21
Soil28 g soil sample was heated to a constant weight of 24g. When further heated to red hot and cooled, it weighed 18 g. What is the percentage of humus in the soil?
- A.22.2
- B.55.6
- C.75.0
- D.25.0
- E.35.7
Show the answer and explanation
Answer: D (25.0)
Explanation
Heating to constant weight drives off water, leaving 24 g of dry soil. Red heat burns off the humus: 24 − 18 = 6 g. Percentage humus in the dry soil = 6/24 × 100 = 25.0%.