GCSE Chemistry (AQA) chapter 5: Energy changes MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
19 exam-style questions on Energy changes, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
4.5.1 Exothermic and endothermic reactions10 questions
4.5.2 Chemical cells and fuel cells9 questions
Ten Energy changes questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. Which reaction is endothermic?
A
respiration in living cells
B
the neutralisation of an acid by an alkali
C
the combustion of methane in a Bunsen burner
D
the thermal decomposition of limestone
Show answer
Answer: D. Thermal decomposition needs a continuous input of energy, so it is endothermic. Combustion, neutralisation and respiration all release energy.
2. On the reaction profile for an exothermic reaction, where are the products?
A
at a lower energy than the reactants
B
at the top of the activation energy hump
C
at a higher energy than the reactants
D
at the same energy as the reactants
Show answer
Answer: A. An exothermic reaction transfers energy to the surroundings, so the products end up with less energy than the reactants.
3. Solid ammonium nitrate dissolves in water in a polystyrene cup and the temperature falls from 21.5 °C to 16.0 °C. Which statement is correct?
A
the change is exothermic and the temperature fell by 5.5 °C
B
the change is endothermic and the temperature fell by 37.5 °C
C
the change is exothermic because energy left the cup
D
the change is endothermic and the temperature fell by 5.5 °C
Show answer
Answer: D. The surroundings lost energy, so energy was taken in by the reaction: endothermic. The fall is 21.5 − 16.0 = 5.5 °C; the temperatures must be subtracted, not added.
4. What is the overall equation for the reaction in a hydrogen fuel cell?
A
2H2O → 2H2 + O2
B
2H2 + O2 → 2H2O
C
H2 + O2 → H2O2
D
H2 + O2 → H2O
Show answer
Answer: B. Adding the two half equations gives 2H2 + O2 → 2H2O. The reverse equation is electrolysis of water.
5. 2H2 + O2 → 2H2O has an energy change of −486 kJ/mol. Bond energies in kJ/mol: H–H 436, O–H 464. What is the O=O bond energy?
A
−498 kJ/mol
B
498 kJ/mol
C
984 kJ/mol
D
1370 kJ/mol
Show answer
Answer: B. Broken − made = −486: (2 × 436 + x) − (4 × 464) = −486, so 872 + x − 1856 = −486 and x = 498 kJ/mol. Bond energies are always positive.
6. What is the only product of the overall reaction in a hydrogen fuel cell?
A
oxygen
B
hydrogen peroxide
C
water
D
carbon dioxide
Show answer
Answer: C. Hydrogen is oxidised by oxygen from the air to make water, so the cell produces no carbon dioxide at the point of use.
7. What is the voltage of a cell made with two electrodes of the same metal in the same electrolyte?
A
the same as a zinc and copper cell
B
double the usual voltage
C
the maximum possible voltage
D
zero
Show answer
Answer: D. Voltage comes from the difference in reactivity between the electrodes. With identical metals there is no difference, so no voltage.
8. What is needed to make a simple chemical cell?
A
two different metals in contact with distilled water
B
two different metals in contact with an electrolyte
C
two different metals that touch each other but no liquid
D
two identical metals in contact with an electrolyte
Show answer
Answer: B. A cell needs two different metals (electrodes) in an electrolyte, which contains ions. Distilled water has almost no ions.
9. Which half equation shows the reaction at the negative electrode of a hydrogen fuel cell?
A
2H+ + 2e− → H2
B
H2 → 2H+ + 2e−
C
O2 → 2O2− + 4e−
D
O2 + 4H+ + 4e− → 2H2O
Show answer
Answer: B. Hydrogen is oxidised (loses electrons) at the negative electrode; the electrons flow round the circuit. Oxygen is reduced at the positive electrode.
10. Which is a disadvantage of hydrogen fuel cells compared with rechargeable batteries?
A
they produce carbon dioxide and water when they are in use
B
they cannot be used to power cars, buses or lorries
C
their voltage falls steadily as the fuel is used up
D
hydrogen is flammable and difficult to store
Show answer
Answer: D. Hydrogen needs high-pressure tanks and is highly flammable. Fuel cells produce only water and keep a steady voltage while fuel is supplied.
19, each with the answer and a short explanation, across 2 topics: 4.5.1 Exothermic and endothermic reactions, 4.5.2 Chemical cells and fuel cells. Every chapter test draws ten of them, so you can take it many times.
Is the GCSE Chemistry (AQA) chapter 5 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
