Science — AI-generated practice question

Activity: Testing whether zinc reacts with dilute sulphuric acid to produce hydrogen gas.

Apparatus/Procedure:
Take about 5 mL of dilute sulphuric acid in a test tube. Add a few pieces of zinc granules to it. Pass the gas evolved through soap solution using a delivery tube. Bring a burning candle near a soap bubble filled with the gas.

Labelled Diagram:

```
[Test tube]
Zn granules + H₂SO₄
|
[Delivery tube]
|
[Soap solution]
(bubbles form)
↑
[Burning candle → brought near bubble]
```
(Label: zinc granules, dilute H₂SO₄, delivery tube, soap solution, gas bubble)

Observations:

1. Brisk effervescence is seen on the surface of zinc granules.
2. Bubbles form in the soap solution, showing gas is being produced.
3. When a burning candle is brought near the gas-filled soap bubble, it burns with a pop sound.

Chemical Equation:
$$\text{Zn(s)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq)} + \text{H}_2\text{(g)}$$

Conclusion: The gas produced is hydrogen. Zinc displaces hydrogen from dilute sulphuric acid, producing zinc sulphate and hydrogen gas.

Source: Chapter 2, Section 2.1.2, Activity 2.3

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• The examiner expects: setup description, a neat labelled diagram, two clear observations (effervescence + pop sound with candle), the balanced equation, and a conclusion. Missing the "pop" sound or the equation loses marks.
• The diagram need not be artistic — labels are what matter. Include: test tube, zinc granules, H₂SO₄, delivery tube, soap solution.
• "Pop sound" is the standard test for hydrogen — always mention it explicitly.
• The balanced equation is already balanced as written (1:1:1:1 ratio), so no coefficients need adjusting.