BIOLOGY

JAMB 2011 - Question 29

Biology 2011 JAMB Past Questions - Question 29: In an experiment to determine the percentage of humus and water in a soil sample, the following results were obtained: Weight of the evaporating basin alone = 80.5g Weight of basin and soil = 101.5g Weight after drying the soil in the oven = 99.0g Weight of basin and roasted soil = 95.5g The percentage of humus in the soil sample is

Choose the most appropriate option for the gap .
In an experiment to determine the percentage of humus and water in a soil sample, the following results were obtained: Weight of the evaporating basin alone = 80.5g Weight of basin and soil = 101.5g Weight after drying the soil in the oven = 99.0g Weight of basin and roasted soil = 95.5g The percentage of humus in the soil sample is
A:
B:
C:
D:
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Correct Answer

C

Explanation

eight of basin + wet soil = 1Q1.5g Weight of basin alone = 80. 5a Weight of wet soil = 21.5g Weight of basin + dry soil = S9.0g Weight of basin = 8Q.5q Weight of dry soil = 18.5g Weight of water= weight of wet soil - dry soil = 21.0-18.5 = 2.5gWeight of basin + roasted (burnt) soli - = 95.5g Weightof basin alone - 80.5qWeightof roasted (burnt) soil = 15.0gWeight of humus=weight of dry soil-weight of roasted soil18.8-15.Og~3.5g Weight cf humus= Weight of humus x100% Weightof wet soil 13.5 x 100% 21 1 ~16.66%