Zone A — Animated concept questions
Select a topic or attempt all 20. Watch the visual carefully before answering.
Zone B — Structured-response studio
Write a concise answer, reveal the marking points, then honestly self-check.
Zone C — Alternative-to-practical laboratory
Interact with simulated data and apply safe, fair-test reasoning.
1. Read the gas syringe
40 cm³
Which apparatus variable must remain constant when comparing two catalysts?
2. Separate a mixture
Why must the starting line be above the solvent and drawn in pencil?
3. Complete and interpret the table
| Time / s | Gas with catalyst A / cm³ | Gas with catalyst B / cm³ |
|---|---|---|
| 0 | 0 | 0 |
| 20 | 34 | 20 |
| 40 | 52 | 39 |
| 60 | 60 | 52 |
| 80 | 60 | 60 |
Which catalyst gives the faster initial rate, and what evidence supports this?
4. Build a fair investigation
A learner compares how quickly equal lengths of magnesium react with hydrochloric acid at different concentrations.
Complete automatic grading
Grades all 30 MCQs, seven structured responses and four practical activities. Short answers are checked against accepted scientific marking points.