Standard Science Primary 4 Matter

A substance is heated at a constant rate. The graph shows its temperature over time. What is happening during the period where the temperature remains constant at 80°C?

A The substance is losing heat.
B The substance is cooling down.
C The substance is boiling.
D The substance is melting.
Show Worked Solution

Worked Solution

Step 1: A horizontal line on a heating graph indicates a change of state. Step [2-9]: During a change of state, temperature remains constant because the heat energy is used to overcome the forces of attraction between particles. Step [2-9]: Since the substance is being heated, this is likely the boiling point.

Correct answer: The substance is boiling.

Want more questions like this? Superholic Lab has 10,000+ MOE-aligned questions with full worked solutions.

Start Free Trial — 7 Days Free