These seven original questions ramp from recall to multi-step reasoning. Attempt each on paper before opening its answer.
Afterwards, check your written answers with the structured answer self-review tool. More topics are in SPM subjects and learning resources.
Questions
Question 1: Magnesium ribbon is held in a flame. State two observations (2 marks).
Answer
The ribbon burns with a bright white light. A white powder is left behind. Both are things you can see, and the powder is magnesium oxide, but naming it is a conclusion and does not earn the observation mark.
Question 2: A potato cylinder of mass 5.0 g is placed in concentrated salt solution for one hour. Its mass becomes 4.2 g. Calculate the percentage change in mass (2 marks).
Answer
Change = 4.2 − 5.0 = −0.8 g.
Percentage change = (−0.8 ÷ 5.0) × 100 = −16%, a decrease of 16%. The divisor is the original mass, not the new one.
Question 3: Explain your answer to Question 2 using the movement of water (2 marks).
Answer
The salt solution is more concentrated than the liquid inside the potato cells. Water moves out of the cells into the solution by osmosis, so the cylinder loses mass.
Question 4: A trolley travels 1.2 m in 3.0 s at a steady speed. Find the speed, then the distance covered in 7.5 s at the same speed (3 marks).
Answer
Speed = 1.2 ÷ 3.0 = 0.40 m/s.
Distance = 0.40 × 7.5 = 3.0 m.
Check by scaling: 7.5 s is 2.5 times 3.0 s, and 1.2 × 2.5 = 3.0 m.
Question 5: The table shows the volume of gas collected from a reaction at different concentrations of acid.
| Concentration (mol/dm³) | Volume of gas in 60 s (cm³) |
|---|---|
| 0.5 | 12 |
| 1.0 | 25 |
| 1.5 | 36 |
| 2.0 | 49 |
Describe the trend and state one limit of your conclusion (3 marks).
Answer
As the concentration increases from 0.5 to 2.0 mol/dm³, the volume of gas in 60 s increases from 12 cm³ to 49 cm³. The volume is close to proportional, about 24 cm³ for each 1.0 mol/dm³. The conclusion applies only between 0.5 and 2.0 mol/dm³, because no higher or lower values were tested.
Question 6: A copper block has mass 267 g and volume 30 cm³. Calculate its density, then the volume of a 445 g block of the same metal (4 marks).
Answer
Density = 267 ÷ 30 = 8.9 g/cm³.
Volume = mass ÷ density = 445 ÷ 8.9 = 50 cm³.
Check: 8.9 × 50 = 445. If you multiplied 445 by 8.9 instead, see the repair lesson linked below.
Question 7: Explain, using an example, why a wider base makes a tall object more stable (3 marks).
Answer
A wider base keeps the line of the weight, acting down from the centre of gravity, inside the base for larger tilts. For example, a wide-based cone on a table must be tilted a long way before it topples, while a thin pole tips after a small tilt. So the wider base gives greater stability.
If you got these wrong
- Questions 1 and 3: review observation versus explanation.
- Questions 5 and 7: review interpreting a small evidence table and explaining with an example.
- Questions 2, 4 and 6: start with repairing a prerequisite.
For a teacher to work through your wrong answers with you, see online one-to-one Additional Science tuition.