Paper 2 Energetics MCQ Practice
10 multiple-choice questions on chemical energetics for IGCSE Chemistry Paper 2. Covers exothermic and endothermic reactions, energy diagrams, bond energies, and activation energy.
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.
Ten multiple-choice questions in the style of IGCSE Chemistry Paper 2. Choose the best answer for each, then check the mark scheme.
Question 1
Which of the following is an exothermic reaction?
A. Thermal decomposition of calcium carbonate B. Photosynthesis C. Dissolving ammonium nitrate in water D. Combustion of methane
Answer
D
Combustion reactions are always exothermic --- they release energy to the surroundings. Thermal decomposition, photosynthesis, and dissolving ammonium nitrate are endothermic processes that absorb energy from the surroundings.
Question 2
In an exothermic reaction, the temperature of the surroundings:
A. decreases B. increases C. stays the same D. first increases then decreases
Answer
B
In an exothermic reaction, energy is transferred from the reaction to the surroundings, causing the temperature of the surroundings to increase. This is why you feel warmth when holding a hand warmer (an exothermic reaction).
Question 3
On an energy level diagram for an exothermic reaction, the products are drawn:
A. at a higher energy level than the reactants B. at the same energy level as the reactants C. at a lower energy level than the reactants D. above the activation energy hump
Answer
C
In an exothermic reaction, the products have less chemical energy than the reactants. The difference in energy levels represents the energy released to the surroundings. The arrow pointing downwards from reactants to products represents a negative enthalpy change.
Question 4
What is activation energy?
A. The total energy released during a reaction B. The minimum energy needed for reacting particles to collide successfully and react C. The energy stored in the products D. The energy difference between reactants and products
Answer
B
Activation energy is the minimum energy that colliding particles must have for a successful collision that leads to a reaction. On an energy diagram, it is shown as the energy difference between the reactants and the top of the energy barrier (the peak of the curve).
Question 5
A catalyst increases the rate of a reaction by:
A. increasing the temperature B. providing an alternative reaction pathway with a lower activation energy C. increasing the concentration of reactants D. increasing the energy of the products
Answer
B
A catalyst provides an alternative reaction pathway with a lower activation energy. This means more particles have enough energy to react in any given collision, so the rate of successful collisions increases. The catalyst is not used up and does not change the products or the overall energy change.
Question 6
Which process is endothermic?
A. Neutralisation B. Respiration C. Dissolving ammonium nitrate in water D. Burning magnesium
Answer
C
Dissolving ammonium nitrate in water is endothermic --- it absorbs energy from the surroundings, causing the temperature to drop. This is used in instant cold packs. Neutralisation, respiration, and burning magnesium are all exothermic.
Question 7
In a bond energy calculation, the overall energy change of a reaction equals:
A. energy to break bonds + energy released making bonds B. energy to break bonds - energy released making bonds C. energy released making bonds - energy to break bonds D. energy released making bonds + energy to break bonds
Answer
B
Energy change = total bond energy of bonds broken - total bond energy of bonds formed. Breaking bonds requires energy (endothermic) and making bonds releases energy (exothermic). If more energy is released making bonds than is needed to break bonds, the reaction is exothermic (negative value).
Question 8
The bond energies are: H-H = 436 kJ/mol, Cl-Cl = 242 kJ/mol, H-Cl = 431 kJ/mol. What is the energy change for H₂ + Cl₂ → 2HCl?
A. -184 kJ/mol B. +184 kJ/mol C. -247 kJ/mol D. +247 kJ/mol
Answer
A
Bonds broken: 1 x H-H (436) + 1 x Cl-Cl (242) = 678 kJ/mol. Bonds formed: 2 x H-Cl (2 x 431) = 862 kJ/mol. Energy change = 678 - 862 = -184 kJ/mol. The negative value confirms the reaction is exothermic.
Question 9
On an energy diagram, adding a catalyst changes:
A. the energy of the reactants B. the energy of the products C. the height of the activation energy barrier D. the overall energy change of the reaction
Answer
C
A catalyst lowers the activation energy barrier. The energy levels of the reactants and products remain unchanged, so the overall energy change (enthalpy change) is the same. Only the activation energy peak is lower on the diagram.
Question 10
During an endothermic reaction in a beaker, the beaker feels cold to touch. This is because:
A. the reaction produces cold particles B. the reaction absorbs energy from the surroundings, including the beaker C. the products move more slowly D. the reaction releases energy as light
Answer
B
In an endothermic reaction, energy is absorbed from the surroundings. The surroundings include the solution, the beaker, and your hand. As energy is transferred from the surroundings to the reaction, the temperature of the surroundings decreases, making the beaker feel cold.
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