MCQ Tip Talk 3: Is there enough information?

[24 Feb 2023]

For ✨MCQ Tip Talk #3, let’s look at another practice question:

Q: Mrs Lim is trying to cool a bottle of hot milk quickly. She places the bottle in a bowl of cold water.

What of the following statement is/are true?
A. The temperature of hot milk decreases.
B. The hot milk loses heat to both the cold water and surrounding air.
C. The cold water gains heat from the surrounding and temperature decreases.
D. When the temperature of hot milk and cold water are the same, that temperature is at room temperature.

(1) A & B only
(2) A & C only
(3) A, B & D only
(4) A, B, C and D only

Let’s Break it Down:

Statement A:
The temperature of hot milk decreases.
✔️This is the correct statement.

Statement B:
The hot milk loses heat to both the cold water and surrounding air.
✔️This is the correct statement.

Statement C:
The cold water gains heat from the surrounding and temperature decreases.
❌1 wrong word – common trick used in MCQs but this is considerably easier to catch. The word should be increases instead of decreases.

[Important] Remember to read the entire statement in order to spot the trick.

Statement D:
When the temperature of hot milk and cold water are the same, that temperature is at room temperature.
❌Not possible to tell! We do not know what is the respective temperature of the hot milk, cold water and surrounding air. We do not know the rate of heat gain/loss too. Hence there is not enough information to determine that temperature of the hot milk and cold water will only be the same when they are at room temperature.

[Important] For Science, we cannot make assumptions unless otherwise stated in the question.

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