Question 1
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Question 1
The diagram below illustrate an experimental set-up on soil samples. Study it and answer the question that follow.
(a) State the aim of the experiment. (1 mark)
(b) Name the soil sample in each of the tubes labelled I, II and III. (3 marks)
(c) Outline the procedure for carrying out the experiment. (5 marks)
(d) State three properties of each soil sample in the tubes labelled I and III. (6 marks)
Observation
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This question was fairly attempted by many candidates.
- Many candidates were unable to state the aim of the capillarity experiment although they could name the soil samples in each tube.
- Majority of the candidates could not correctly outline the procedure for carrying out the capillarity experiment.
The expected answers include:
1. . (a) Aim of the experiment
- To compare the capillarity/capillary action of different soil samples
(b) Naming of soil samples in the glass tubes
I - Sandy soil/sand
II - Loamy soil/loam
III - Clay soil/clay
(c) Procedure for carrying out the experiment
- Obtain three long glass tubes
- Close the lower end of each glass tube with cotton wool
- Grind/sieve the soil samples after air drying
- Fill the tubes with equal volumes of sand, loam and clay soil
- Immerse the lower end of each tube in a water trough
- Allow the set-up to stand overnight/some hours(d) Properties of soil samples in the tubes labelled I (Sandy soil) and III (Clay soil)
I (Sandy soil)
- Low capillary action - Low water holding/retention capacity
- Coarse grained - Large pore spaces
- Not sticky when wet - Gritty to touch
- Easily gets hot or cold - Well aerated
- Grey/brown in colour - Particles are large
III(Clay soil)
- High capillary action - High water holding/retention capacity
- Fine grained - Fine/small pore spaces
- Smooth to touch - Does not easily get hot or cold
- Brown/red/grey in colour - Sticky when wet/forms ribbon when wet