John saw many tadpoles in a pond in his school eco-garden. He wanted to find out which type of water, pond water or tap water, is more suitable for the tadpoles to grow healthily. He caught the tadpoles and placed them in 2 identical containers as shown below. He placed the containers in the same room. However, his teacher told him that his experiment was not a fair one.

A. Give two reasons why his test was not a fair one.

1.

2.

2 small identical steel balls were put in beakers X and Y which were filled with hot boiling water. Which of the following statements are correct?

A: Both metal balls increase in size after a while.

B: Heat from hot water is transferred to these two balls.

C: The water in beaker X lost heat slower than the water in beaker Y.

D: Steel ball in beaker X obtained heat slower than the ball in beaker Y.

1. A and B

2. A and C

3. B and D

4. C and D

3 set of similar rings shown below are made from four different types of metals A, B, C and D.

At 27°C, all the inner rings of each set are able to fit into the outer ring and still can be pulled out with some force. The sets of rings were then heated from 27°C to 60°C and below are some observation made at 60°C.

Set X: The inner ring just fit into the outer ring and can be removed out with a small force.

Set Y: The inner ring fell out easily.

Set Z: The inner ring could not be moved out even when a great force was applied.

Based on the above statements, which metal expanded the most when heated?

1. A            2. B            3. C        4. D

Amy wants to show that photosynthesis needs carbon dioxide to take place. She intends to carry out starch tests on some leaves to help her in theinvestigation. She uses 4 similar plants of similar size and sets up the experiment as shown. All setups are exposed to the sunlight, except Set-up A, which is placed in the dark.

Which two of the set-ups should she use to make a valid conclusion?

1. C and D only

2. B and D only

3. A and C only

4. A and B only