Topic 1 of 8
Read unfamiliar data
Select evidence and connect it to a chemical principle.
O-Level 5086 / 5088 (2026) / SEC G3 K326 / K328 (2027)
Read unfamiliar data with a purpose
Separate the question, the evidence and the chemistry that connects them.
Start with the quantity or claim the question asks you to establish. Then locate the relevant measurements, conditions and any new definitions in the stem. An unfamiliar substance name does not make its data unusable: use the supplied information together with a familiar idea such as conservation of atoms, collision frequency or intermolecular attraction.
- Name the task
For a calculation, identify the required quantity and unit. For an explanation, identify the observation that needs explaining.
- Select the evidence
Extract the relevant rows, axes and conditions. Distinguish a measurement from a proposed explanation; do not use every number just because it is present.
- Connect a principle
State the chemical relationship that makes the evidence relevant. Check that the comparison holds other important variables constant.
- State the result and its limit
Give a numerical answer with units, or a conclusion supported by a specific comparison. State an assumption where the inference depends on it.
Worked example
Assess a claim about a catalyst
Two runs use the same amount of reactant and the same temperature. Run A gives 40 cm3 of gas in 20 s; run B gives 40 cm3 in 50 s. Both eventually give 60 cm3. A report says: "A produces more product because it is faster."
- The time to reach the same volume is smaller for A: its average rate to 40 cm3 is 2.0 cm3 s-1, compared with 0.80 cm3 s-1 for B.
- The final volumes are the same under the same collection conditions, so these data do not show more final gaseous product in A.
- The evidence supports faster production, not a greater final amount. Identifying the cause as a catalyst also requires the stated experimental difference between the runs.
Compare rate using a time interval and final amount using the plateau. They answer different questions.
A useful explanation joins evidence and mechanism: "At the same temperature, the more concentrated acid gives a higher measured reaction rate. More reacting particles per unit volume cause more frequent collisions with the metal surface." State the controlled conditions and explain the observed trend, rather than merely repeating that a graph is higher.