JAMB - Biology (1989 - No. 39)

5 g of oven dried soil was heated in a furnace for 24 hours. After cooling, it weighed 4.8 g. What is the amount of humus in the soil?

40.0g per 100 g dry soil

4.4g per 100g dry soil

4.0 g per 100g dry soil

0.4g per 100g dry soil

Mass of soil before drying, M\(_1\) = 5g

Mass of soil after drying, M\(_2\) = 4.8g

Difference in mass,M\(_1\) - M\(_2\) = 5 - 4.8g = 0.2g

Amount of humus in the soil = \(\frac{{M_1} - {M_2}}{M_1}\times 100\)

= \(\frac{0.2}{5}\times 100\)

= 4.0g per 100 dry soil