Questions about Endothermic Reactions
Multiple-choice questions about Endothermic Reactions, each with five answer options. The correct answers with full explanations are provided at the end.
Multiple-Choice Questions – Endothermic Reactions
1. What best defines an endothermic reaction?
A) A reaction that releases heat
B) A reaction that releases light
C) A reaction that absorbs heat
D) A reaction with no energy change
E) A reaction that only occurs in gases
2. In an endothermic reaction, energy is:
A) Released to the surroundings
B) Transferred only as light
C) Absorbed from the surroundings
D) Not involved
E) Constant
3. Which of the following processes is an endothermic reaction?
A) Freezing water
B) Burning wood
C) Melting ice
D) Condensation of vapor
E) Neutralization of acid and base
4. What is the sign of ΔH for an endothermic reaction?
A) ΔH = 0
B) ΔH > 0
C) ΔH < 0
D) ΔH = –∞
E) ΔH = constant
5. Which observation indicates that a reaction is endothermic?
A) The container becomes warm
B) Light is emitted
C) Temperature of surroundings decreases
D) Gas is released
E) A solid is formed
6. Which phase change is an example of an endothermic process?
A) Condensation
B) Deposition
C) Freezing
D) Melting
E) Combustion
7. Endothermic reactions are often characterized by:
A) A release of energy
B) A gain of thermal energy
C) No energy exchange
D) An explosion
E) Sudden color change
8. An ice pack used for sports injuries becomes cold due to:
A) An exothermic reaction
B) Friction
C) An endothermic reaction
D) Radiation
E) Decomposition of gas
9. Which chemical process is typically endothermic?
A) Combustion of hydrocarbons
B) Photosynthesis
C) Rusting of iron
D) Neutralization
E) Condensation of water
10. When energy is absorbed in a reaction, the products have:
A) Less energy than the reactants
B) The same energy as the reactants
C) More energy than the reactants
D) No energy at all
E) Infinite energy
11. In an endothermic reaction, the temperature of the surroundings:
A) Increases
B) Stays the same
C) Decreases
D) Becomes extremely hot
E) Causes ignition
12. Which of the following is NOT an endothermic process?
A) Melting
B) Vaporization
C) Sublimation
D) Condensation
E) Cooking an egg
13. Why does the temperature decrease during an endothermic reaction?
A) Energy is destroyed
B) Energy is converted to matter
C) Heat is absorbed from the surroundings
D) Molecules stop moving
E) Pressure increases
14. Which situation describes an endothermic reaction?
A) Water freezing on a winter day
B) Steam condensing on a mirror
C) Baking bread in an oven
D) Burning coal
E) Lighting a candle
15. What is required for an endothermic reaction to proceed?
A) A catalyst
B) External heat or energy
C) Light source only
D) No energy
E) Radioactivity
16. Endothermic reactions typically feel:
A) Warm
B) Cold
C) Neutral
D) Explosive
E) Sticky
17. In an endothermic reaction, energy is stored:
A) In the surroundings
B) As light
C) In the products
D) In the reactants
E) In the air
18. Which reaction is most likely endothermic?
A) Condensation of steam
B) Burning magnesium
C) Dissolving ammonium nitrate in water
D) Freezing point depression
E) Firework explosion
19. Which of the following reactions would have a positive ΔH value?
A) Exothermic reaction
B) Endothermic reaction
C) Combustion reaction
D) Neutralization
E) Oxidation of glucose
20. What happens to the enthalpy in an endothermic process?
A) It remains constant
B) It decreases
C) It becomes negative
D) It increases
E) It cannot be measured
Answers with Explanations
1. C – An endothermic reaction absorbs heat from the surroundings.
2. C – The defining trait of endothermic reactions is energy absorption.
3. C – Melting ice absorbs heat, making it endothermic.
4. B – A positive ΔH indicates energy is absorbed.
5. C – The surroundings lose heat, so their temperature drops.
6. D – Melting requires heat input, so it’s endothermic.
7. B – Thermal energy enters the system in endothermic reactions.
8. C – Sports cold packs cool via endothermic reactions.
9. B – Photosynthesis requires sunlight (energy input).
10. C – Products of endothermic reactions have more stored energy.
11. C – Heat leaves surroundings and enters the system.
12. D – Condensation releases energy (it's exothermic).
13. C – Heat is absorbed by the system, cooling surroundings.
14. C – Baking absorbs heat, thus it's endothermic.
15. B – Endothermic reactions need energy to begin or sustain.
16. B – They absorb heat, so they feel cold.
17. C – Energy is stored in the chemical bonds of the products.
18. C – Dissolving ammonium nitrate is a common endothermic example.
19. B – Endothermic reactions always have positive ΔH.
20. D – Enthalpy increases due to energy absorption.
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