In an experiment the surfaces of three iron nails were cleaned dry and placed in three separate test tubes A, B and C as shown in the diagram.

Study the diagram carefully and answer the questions that follow.

After three days the nail in the test tube A was found to have rusted while the nail in test tubes B and C did not rust

1. Suggest an aim for the experiment.

2. Why was the water in test tube B boiled?

3. State the function of the oil on top of the water in test tube B.

4. What is the purpose of the calcium chloride in test tube C?

5. Why did the nail in test tube A rust?

6. Why did the nail in test tube

   α) B not rust?

   β) C not rust?

7. From the experiment, explain why oil is applied on the surface of a metal to prevent rusting.

In an experiment, the following activities were carried out on two green leaves A and B.Leaf A was taken from a plant placed in the sunlight for some time while leaf B was taken from a plant placed in a dark cupboard for 24 hours.
Activity

1. Leaves dipped in boiling water for 1 minute;

2. Leaves dipped in warm alcohol;

3. Leaves washed in cold water;

4. Leaves dipped in iodine solution.

After dipping in the iodine solution, it was observed that leaf A changed colour.

Study the activities carefully and answer the questions that follow.

1. Suggest an aim for the experiment.

2. Explain briefly why each of the following activities were carried out:

   α) I

   β) II

   γ) III

3. State the colour change of leaf A.

4. Explain why leaf A changed colour?

5. Why is it necessary to de-starch the plant before starting the experiment?

6. From the above experiment, what conclusion(s) can be drawn.

You are provided with two dry soil samples A and B, a measuring cylinder, beakers, funnels, filter paper, beam balance, stop watch and water. With the aid of a labelled diagram, describe an experiment to find out which of the two soil samples can hold more water.

The diagram below is an illustration of an experiment that was carried out. In the experiment three pins 1, 2 and 3 were fixed with candle wax onto a metal bar and one end of the bar was heated by means of boiling water. A, B and C are thermometers inserted in holes along the bar to measure the temperature at the various points

Study the diagram carefully and answer the questions that follow.

1. Suggest an aim for the experiment.

2. What is the temperature of the boiling water?

3. State the observation that would be made about the pins 1, 2 and 3.

4. State the observation that would be made about the temperatures recorded by the thermometers A, B and C.

5. State how heat from the sun is transmitted to the earth.