A student adds 1.00 g of each of four metal oxides to separate portions of the same hydrogen peroxide solution. She times how long it takes to collect 50 cm350\,\mathrm{cm^{3}}50cm3 of oxygen, then filters, dries and weighs the solid left.
| Solid added | Time to collect 50 cm350\,\mathrm{cm^{3}}50cm3 of oxygen / s | Mass of solid recovered / g |
|---|---|---|
| no solid | 300 | not applicable |
| oxide P | 20 | 1.00 |
| oxide Q | 15 | 0.62 |
| oxide R | 300 | 1.00 |
| oxide S | 60 | 1.00 |
Which conclusion is best supported by the data?
P is the most effective catalyst, as it is fast and is not used up
Q is the most effective catalyst, as it produces oxygen the fastest
R is a catalyst, as its mass is the same at the end as at the start
P and Q are both catalysts, as both speed up the reaction a lot
42 exam-style questions on Edexcel GCSE Chemistry 6.1 Transition metals, alloys and corrosion, covering 6.1.1 Properties of transition metals, 6.1.2 Corrosion and its prevention, and 6.1.3 Alloys and the uses of metals. Each one has a worked solution and a mark scheme showing where the marks go.