Questions about Exothermic Reactions
multiple-choice questions about Exothermic Reactions, each with five alternatives. The answers with full explanations are provided at the end.
Multiple-Choice Questions – Exothermic Reaction
1. What is an exothermic reaction?
A) A reaction that absorbs heat
B) A reaction with no temperature change
C) A reaction that releases heat
D) A reaction that releases light only
E) A reaction that involves only physical changes
2. Which of the following is typically true for exothermic reactions?
A) The products have more energy than the reactants
B) Energy is stored in the system
C) The temperature of the surroundings decreases
D) The reaction container feels warm
E) The reaction is always slow
3. Which of the following is an example of an exothermic reaction?
A) Melting ice
B) Photosynthesis
C) Combustion of methane
D) Boiling water
E) Dissolving ammonium nitrate in water
4. In an exothermic reaction, how does the enthalpy (ΔH) change?
A) ΔH is zero
B) ΔH is positive
C) ΔH is negative
D) ΔH is infinite
E) ΔH is always increasing
5. Which graph shape correctly represents an exothermic reaction energy profile?
A) Energy of products is higher than reactants
B) Flat line
C) Energy of products is lower than reactants
D) Energy constantly increases
E) Reactants and products at the same energy level
6. The combustion of gasoline is:
A) Endothermic
B) Exothermic
C) Neither
D) Physical change
E) Reversible without energy
7. Which sign of ΔH indicates that a chemical reaction is exothermic?
A) +ΔH
B) –ΔH
C) ΔH = 0
D) ΔH = ∞
E) None of the above
8. Why do exothermic reactions feel hot to the touch?
A) They absorb heat from your hand
B) They increase evaporation
C) They release heat to the surroundings
D) They reduce energy in the body
E) They freeze water
9. Which reaction type is typically exothermic?
A) Evaporation
B) Condensation
C) Electrolysis
D) Photosynthesis
E) Dissociation of salts in water
10. What occurs to the surroundings in an exothermic reaction?
A) Absorb energy
B) Cool down
C) Gain heat
D) Form a solid
E) Emit light only
11. In an exothermic reaction, how does the bond energy of the products compare to the reactants?
A) More energy is required to break the bonds
B) Bond energy is higher in the products
C) Bond energy is higher in the reactants
D) Bond energy remains constant
E) No bonds are broken or formed
12. Which of the following processes is not exothermic?
A) Freezing of water
B) Condensation of steam
C) Combustion of propane
D) Evaporation of alcohol
E) Reaction of acid and base
13. Which of the following is most likely to be an exothermic chemical change?
A) Cooking an egg
B) Rusting of iron
C) Exploding firework
D) Melting butter
E) Boiling liquid nitrogen
14. What best describes the energy transfer in an exothermic process?
A) Energy is absorbed from surroundings
B) Energy is released to the surroundings
C) Energy remains constant
D) Energy is stored in the products
E) Energy is transferred as sound
15. Which of the following temperature changes indicates an exothermic reaction?
A) No change in temperature
B) Decrease in temperature
C) Increase in temperature
D) Temperature drops suddenly
E) System remains at freezing point
16. What type of reaction is neutralization of a strong acid and strong base?
A) Always endothermic
B) Neither endo- nor exothermic
C) Always exothermic
D) It depends on the temperature
E) Only exothermic in gases
17. In terms of potential energy, exothermic reactions...
A) Increase potential energy of the system
B) Have products with higher potential energy
C) Have products with lower potential energy
D) Maintain potential energy
E) Gain energy from the air
18. Exothermic reactions are often used in:
A) Instant cold packs
B) Photosynthesis
C) Cooking food
D) Fireplaces and heating
E) Freezers
19. Which phase change is exothermic?
A) Melting
B) Vaporization
C) Sublimation
D) Condensation
E) Boiling
20. What is a common feature of all exothermic reactions?
A) The system gains heat
B) They absorb thermal energy
C) Heat is released into the surroundings
D) No temperature change occurs
E) The products feel cold
Answers with Explanations
1. C – Exothermic reactions release heat to their surroundings.
2. D – The container feels warm because heat is released.
3. C – Combustion is a classic exothermic process.
4. C – ΔH is negative in exothermic reactions, showing energy release.
5. C – Energy of products is lower than reactants, indicating energy loss.
6. B – Combustion reactions are always exothermic.
7. B – A negative enthalpy change (–ΔH) indicates an exothermic reaction.
8. C – Heat is released to surroundings, making them feel warm.
9. B – Condensation releases heat, hence exothermic.
10. C – The surroundings gain heat in exothermic reactions.
11. C – Reactants have more bond energy than products in exothermic reactions.
12. D – Evaporation requires energy (endothermic), not releases it.
13. C – Fireworks involve energy release (light, heat, sound).
14. B – Exothermic reactions transfer energy to surroundings.
15. C – Temperature increases in the surroundings.
16. C – Strong acid/base neutralizations are exothermic.
17. C – Products have lower potential energy than reactants.
18. D – Fireplaces use exothermic combustion reactions to produce heat.
19. D – Condensation releases energy (gas → liquid), thus exothermic.
20. C – All exothermic reactions release heat to their environment.
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