PSLE Science Physics Topics 2

Question 1

What is the boiling point of water at standard pressure?

Accepted Answer

100°C

Answer

Water boils at 100°C (212°F) at standard atmospheric pressure (1 atm).

Question 2

Which of the following is an example of a reversible change?

Accepted Answer

Melting ice

Answer

Melting ice is reversible — ice can melt to water and water can freeze back to ice. Burning and cooking cannot be reversed.

Question 3

What type of energy is stored in food?

Accepted Answer

Chemical energy

Answer

Food stores chemical energy in the bonds of its molecules. When we digest food, this energy is released for our body to use.

Question 4

In a simple electrical circuit, what does a switch do?

Accepted Answer

Controls the flow of current by opening or closing the circuit

Answer

A switch controls whether current flows by opening (breaking) or closing (completing) the circuit.

Question 5

Which material is a good insulator of heat?

Accepted Answer

Wood

Answer

Wood is a poor conductor of heat (good insulator), which is why pot handles are often made of wood to prevent burns.

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