Formula practice with units beats re-reading notes. Every question here states its unit.
Syllabus code 0625 · checked against the board on 2026-09-13 · 8 questions available on this subject's topics (19 marks)
Which instrument is most suitable for measuring 25.0 cm³ of dilute acid to the nearest 0.1 cm³?
1 mark · Choose · Units, measuring instruments and significant figures
Answer: Burette
Instrument questions are answered in two steps: what precision is demanded, then which instrument provides at least that precision.
A learner of mass 45 kg climbs a 4.0 m staircase in 6.0 s. Take g = 10 N/kg. Calculate the power she develops.
3 marks · Calculate · Work, energy, power and cost of electricity
Answer: 300 W
Energy first, power second. Answers that go straight to a power formula without showing the 1800 J normally lose the first mark.
0.50 kg of water is heated from 20 °C to 60 °C. The specific heat capacity of water is 4200 J/kg°C. Calculate the energy supplied.
3 marks · Calculate · Heat, temperature and specific heat capacity
Answer: 84 000 J (8.4 × 10⁴ J)
The temperature change is 40, not 60. Working out Δθ as its own step prevents the single most common error in this question.
A radio station broadcasts at a frequency of 9.0 × 10⁷ Hz. The speed of light is 3.0 × 10⁸ m/s. Calculate the wavelength of the waves.
3 marks · Calculate · Waves, sound and light
Answer: 3.3 m (3.33 m)
Dividing powers of ten: subtract the indices. 10⁸ ÷ 10⁷ = 10¹, leaving 30 ÷ 9, which is 3.3.
Two 6.0 Ω resistors are connected in parallel. What is their combined resistance?
1 mark · Calculate · Circuits, resistance and electrical power
Answer: 3.0 Ω
Two equal resistors in parallel always give half the value. Knowing that lets you check every answer in one second.
A student has two lamps and one battery. Describe what happens when the lamps are connected in series, then compare that with connecting them in parallel, referring to current, p.d. and brightness in each case.
4 marks · Compare · Circuits, resistance and electrical power
Answer: Series: one path, same current through both lamps, p.d. shared, both dimmer. Parallel: two paths, same p.d. across each lamp, larger total current from the battery, each lamp at normal brightness.
Write comparisons as pairs — one sentence with "whereas" in the middle scores two marks that two separate paragraphs do not.
A car travels 150 m in 12 s. What is its average speed?
1 mark · Calculate · Forces, moments and motion
Answer: 12.5 m/s
Estimate before you divide: 150 m in 12 s must be a little over 10 m/s, which rules out three of the four options immediately.
A bottle of ammonia is opened at one end of a classroom. Explain, in terms of particles, why the smell is noticed at the other end of the room several seconds later.
3 marks · Explain · Particles, states and separation techniques
Answer: Ammonia particles move randomly and spread out (diffuse) from where there are many to where there are few, colliding with air particles on the way.
"Gas spreads" earns nothing. Name the particles, say they move randomly, and say the direction of movement is from high to low concentration.