Answering Suggest Questions in IGCSE Chemistry
How to handle suggest questions in IGCSE Chemistry 0620. What the examiner expects when the answer is not in the textbook.
Published by IGCSEChemistry.com.my
Chemistry teaching team: K. S. Tan (15+ years teaching IGCSE Chemistry) and Ms Yash (10+ years teaching IGCSE Chemistry) and Ms Kartini (15+ years teaching IGCSE Chemistry).
Mapped to Cambridge IGCSE Chemistry 0620 (2026–2028). Last updated 2026-08-19.
Suggest questions appear on Paper 4 and are designed to test application, not recall. There is no single textbook answer to memorise. Instead, the examiner gives you an unfamiliar scenario and asks you to propose a plausible explanation, improvement, or reason using your chemistry knowledge. This is the command word that unsettles students most, but it is also the most forgiving, because multiple answers can score.
How suggest questions work
The mark scheme for a suggest question lists several acceptable responses (often 4-6 possibilities) and awards the mark for any one of them. This means you do not need to guess what the examiner was thinking; you need to give any scientifically reasonable answer that fits the context.
Example: “Suggest why the student’s percentage yield was lower than expected.” (1 mark)
Mark scheme accepts any of:
- Some product was lost during transfer between containers.
- The reaction did not go to completion.
- Some product was left on the filter paper.
- Some solution was lost during evaporation (spitting).
- Impurities in the reactants reduced the effective mass.
Any one of these earns the mark. But “the student did the experiment wrong” does not, because it is too vague.
The common suggest question types
Type 1: suggest a source of error
“Suggest why the student’s results were different from the expected value.”
Answer framework:
- Identify a specific, practical error: imprecise measuring, contamination, heat loss, incomplete reaction, loss of product during transfer.
- Name the error precisely: “some gas escaped before the bung was fitted” is better than “the experiment was inaccurate.”
Type 2: suggest an improvement
“Suggest how the experiment could be improved to give more accurate results.”
Answer framework:
- Address a specific limitation: “use a more precise measuring instrument (burette instead of measuring cylinder)” or “repeat the experiment and calculate a mean.”
- The improvement must match the error. If the problem is heat loss, the improvement is insulation, not a better balance.
Type 3: suggest a reason for an observation
“The student noticed that the temperature did not rise as much as expected. Suggest a reason.”
Answer framework:
- Link the observation to a chemical or physical cause: “heat was lost to the surroundings,” “the acid was more dilute than stated,” “the reaction is not as exothermic as the data book value because of heat loss.”
Type 4: suggest why a substance/method was chosen
“Suggest why the manufacturer uses this catalyst rather than a different one.”
Answer framework:
- Think about cost, availability, effectiveness, safety, environmental impact: “the catalyst is cheaper,” “it works at a lower temperature, reducing energy costs,” “it is less toxic.”
Type 5: suggest what would happen in an unfamiliar situation
“Element X is in Group VII. Suggest what would happen if element X were added to potassium iodide solution.”
Answer framework:
- Apply the general principle to the new context: “if X is above iodine in Group VII (more reactive), X would displace iodide ions, turning the solution brown as iodine is released.”
- State any assumptions you are making.
The rules for suggest answers
- Be specific. Vague answers earn nothing. “Experimental error” is not specific. “Some gas escaped before the bung was inserted” is specific.
- Be scientifically plausible. The answer must make chemical or physical sense. “The particles forgot to react” is not plausible.
- Match the context. Read the question carefully. If it describes a specific apparatus or procedure, your suggestion must relate to that apparatus or procedure.
- Use chemistry vocabulary. “Heat loss to the surroundings” scores where “it cooled down” might not.
- Do not hedge with multiple contradictory answers. If you write two contradictory suggestions, the examiner marks the first one. If it is wrong, they do not credit the second.
Worked exam question
Q (Paper 4): A student adds a piece of magnesium to copper sulfate solution and measures the temperature change. The temperature rise measured was 8 degrees C, but the theoretical value is 12 degrees C.
(a) Suggest one reason why the temperature rise was lower than expected. (1) (b) Suggest one improvement the student could make to get a result closer to the theoretical value. (1)
Model answer: (a) Heat was lost to the surroundings / the beaker / the air during the reaction (1). (b) Use an insulated container (polystyrene cup) to reduce heat loss (1).
Alternative acceptable answers for (a): the magnesium was oxidised on its surface so less pure metal reacted; the copper sulfate was more dilute than expected. For (b): use a lid on the container; use a more precise thermometer.
The examiner does not expect one right answer; they expect one good answer.
If suggest questions are causing anxiety, the fix is practising them with mark schemes so you learn the range of what is accepted. A trial lesson can build confidence by working through real suggest questions from past papers.