These eight questions are original and move from naming to judging. Write your answer on paper first, then open the model answer.
They follow the lessons in chemistry in health contexts. For a related set that focuses on data, see the health-themed practice questions.
Questions 1 to 4: categories and claims
Question 1. An invented antacid tablet contains magnesium hydroxide. State the type of reaction between the tablet and stomach acid, and name the kind of substance formed besides water.
Answer
It is a neutralisation reaction. The other product is a salt, here magnesium chloride, because the stomach acid is hydrochloric acid.
This describes the chemistry only. It does not say when anyone should take a tablet.
Question 2. Match each category to its general purpose: analgesic, antibiotic, antacid. Purposes: (i) reduces acid, (ii) relieves pain, (iii) acts on bacteria.
Answer
Analgesic matches (ii).
Antibiotic matches (iii).
Antacid matches (i).
An antibiotic acts on bacteria, so it does not act on a virus. That one point can earn a mark in this topic.
Question 3. An advertisement says, “Scientists love this gel, so it works.” Identify the weakness in the claim.
Answer
“Scientists love it” is an opinion with no data behind it. There is no test, no comparison group and no measurement.
A stronger claim would name what was measured, how many samples were used and whether the test was repeated.
Question 4. Tube A of saliva-like solution is treated with a product and its pH rises from 5 to 7, while untreated tube B stays at pH 5. State what this shows and one thing it does not show.
Answer
It shows that the product raised the pH in this test, because tube B acts as a control. It does not show that the product prevents any health problem, because only pH was measured in a test tube.
Questions 5 to 8: labels and limits
Question 5. An invented drink label reads: Energy 180 kJ per 100 ml; Sugar 9 g per 100 ml; bottle size 350 ml. Calculate the sugar in the whole bottle.
Answer
350 ÷ 100 = 3.5 servings of 100 ml. Sugar = 3.5 × 9 = 31.5 g.
The common slip is to read 9 g as the amount in the whole bottle. Check the unit column before calculating.
Question 6. The Question 5 label says “Low in fat”, with 0.3 g of fat per 100 ml. Is that enough to call the drink healthy? Give a reason.
Answer
No. Fat is one nutrient, and the same label shows 31.5 g of sugar per bottle. A single favourable line does not describe the whole product.
The answer is about reading the label fully, not about what a person should drink.
Question 7. A classroom experiment shows that vitamin C solution decolourises a blue dye faster than plain water does. A student concludes, “Vitamin C cures colds.” Correct the conclusion.
Answer
The test shows vitamin C reacts with the dye. A dye in a beaker is not a body, and a colour change says nothing about a cold.
Correct conclusion: vitamin C reacted with the dye under these test conditions.
Question 8. Give two reasons why one classroom example cannot be used to decide how a real medicine works in the body.
Answer
Any two: a classroom example uses simple, pure substances; it ignores other chemicals in the body; it is a model that leaves out dose, time and differences between individuals; and it is usually one test, not many repeats.
If you got these wrong, where do you go next?
Questions 3 and 4 point to distinguishing scientific evidence from marketing claims. Questions 5 and 6 point to reading supplied product information critically.
Questions 7 and 8 point to recognising the limits of a classroom example. Keep a note of each slip in the mistake log and paper-error review, and see online one-to-one Science tuition if the same type keeps returning.