Questions on Single-Replacement Reactions
Single-Replacement Reactions – Multiple Choice Questions
1. What is a single-replacement reaction?
A) A compound forms from simpler substances
B) A compound breaks into simpler substances
C) An element replaces another in a compound
D) Two compounds exchange ions
E) An acid reacts with a base
2. Which of the following is a correct example of a single-replacement reaction?
A) 2Na + Cl₂ → 2NaCl
B) Zn + 2HCl → ZnCl₂ + H₂
C) NaOH + HCl → NaCl + H₂O
D) CaCO₃ → CaO + CO₂
E) 2H₂ + O₂ → 2H₂O
3. In a single-replacement reaction, what determines whether the reaction occurs?
A) Color of the compounds
B) Amount of reactants
C) Activity series of the elements
D) Presence of water
E) Presence of acid
4. Which element can replace hydrogen in an acid?
A) Carbon
B) Helium
C) Copper
D) Zinc
E) Argon
5. Which of the following reactions will not occur?
A) Mg + HCl → MgCl₂ + H₂
B) Zn + CuSO₄ → ZnSO₄ + Cu
C) Cu + AgNO₃ → Cu(NO₃)₂ + Ag
D) Ag + HCl → no reaction
E) Cl₂ + NaBr → NaCl + Br₂
6. What is the product of: Fe + CuSO₄ → ?
A) FeSO₄ + Cu
B) CuFe + SO₄
C) Fe₂SO₃ + Cu₂
D) FeCu + SO₄
E) Cu + Fe₂O₃
7. What type of element generally replaces hydrogen in acids?
A) Noble gases
B) Nonmetals
C) Alkali metals
D) Halogens
E) Metalloids
8. Which of the following represents a halogen replacement reaction?
A) F₂ + 2KBr → 2KF + Br₂
B) Na + H₂O → NaOH + H₂
C) Ca + HCl → CaCl₂ + H₂
D) Cu + AgNO₃ → Cu(NO₃)₂ + Ag
E) 2Al + Fe₂O₃ → Al₂O₃ + 2Fe
9. Which of the following metals will not replace hydrogen in water?
A) Lithium
B) Calcium
C) Zinc
D) Potassium
E) Copper
10. What is the correct product of: Cl₂ + 2NaI → ?
A) I₂ + 2NaCl
B) Cl + NaI₂
C) NaCl + I
D) ICl + Na
E) NaICl₂
11. What is the driving force behind single-replacement reactions?
A) Decrease in temperature
B) Formation of a gas
C) Formation of a precipitate
D) A more reactive element displacing a less reactive one
E) Production of water
12. Which is the most reactive halogen?
A) Iodine
B) Bromine
C) Fluorine
D) Chlorine
E) Astatine
13. In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, zinc is acting as:
A) A reducing agent
B) An oxidizing agent
C) A spectator ion
D) A compound
E) A catalyst
14. What happens to the less reactive element in a single-replacement reaction?
A) It becomes oxidized
B) It gets reduced
C) It stays in the compound
D) It is released as a gas
E) It becomes part of the new solution
15. Which of these reactions involves a metal replacing another metal?
A) Zn + 2HCl → ZnCl₂ + H₂
B) Cu + AgNO₃ → Cu(NO₃)₂ + Ag
C) Cl₂ + NaBr → NaCl + Br₂
D) NaOH + HCl → NaCl + H₂O
E) 2H₂ + O₂ → 2H₂O
16. What does the activity series predict?
A) Atomic number of elements
B) Reactivity of acids
C) Whether a single-replacement reaction will occur
D) The energy of reaction
E) The pH of a solution
17. Which of the following statements is TRUE?
A) A less reactive metal can replace a more reactive one
B) Halogens can't replace halogens
C) Reactions depend on the atomic mass only
D) More reactive elements replace less reactive ones in compounds
E) Noble gases can undergo single-replacement reactions
18. What is a key indicator that a metal has replaced hydrogen in acid?
A) Heat is absorbed
B) Gas bubbles form
C) A colorless solution
D) A solid precipitate
E) No change occurs
19. Which of these will not react with HCl to produce H₂ gas?
A) Mg
B) Zn
C) Cu
D) Fe
E) Al
20. What is the product of: Br₂ + 2KI → ?
A) KBr + I₂
B) Br + KI₂
C) BrI + K
D) IBr + K₂
E) KBr₂ + I
Answers with Explanations
1. C – A single-replacement reaction involves one element replacing another in a compound.
2. B – This is a typical metal-acid single-replacement reaction.
3. C – The activity series determines whether a replacement will occur.
4. D – Zinc is a reactive metal and can replace hydrogen.
5. D – Silver is less reactive than hydrogen and won't replace it.
6. A – Iron replaces copper, forming FeSO₄ and Cu.
7. C – Alkali metals are highly reactive and can replace hydrogen.
8. A – Halogens can replace less reactive halogens (F₂ replaces Br⁻).
9. E – Copper is not reactive enough to replace hydrogen in water.
10. A – Chlorine replaces iodine, forming NaCl and I₂.
11. D – The more reactive element displaces the less reactive one.
12. C – Fluorine is the most reactive halogen.
13. A – Zinc loses electrons and is oxidized, so it's the reducing agent.
14. C – The less reactive element stays in the compound (is not replaced).
15. B – Copper replaces silver in this metal-metal replacement.
16. C – The activity series predicts reaction feasibility.
17. D – Reactivity governs displacement; more reactive replaces less reactive.
18. B – Gas bubbles indicate hydrogen gas formation.
19. C – Copper is below hydrogen in the activity series; no reaction occurs.
20. A – Bromine replaces iodine, forming KBr and I₂.
Teachers can apply this topic through the following activities:
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