Questions on Double-Replacement Reactions
Double-Replacement Reactions – Multiple-Choice Questions
1. What defines a double-replacement reaction?
A) One element replaces another in a compound
B) Two compounds exchange ions to form two new compounds
C) A compound decomposes into elements
D) A compound reacts with oxygen
E) A metal displaces hydrogen from acid
2. Which of the following is an example of a double-replacement reaction?
A) Na + Cl₂ → NaCl
B) AgNO₃ + NaCl → AgCl + NaNO₃
C) Zn + HCl → ZnCl₂ + H₂
D) C₃H₈ + O₂ → CO₂ + H₂O
E) CaCO₃ → CaO + CO₂
3. What must be true for a double-replacement reaction to occur?
A) Both reactants must be acids
B) One product must be a solid, gas, or water
C) The reaction must release heat
D) Oxygen must be present
E) One reactant must be a metal
4. What is a precipitate in a double-replacement reaction?
A) A solid formed and settles out of solution
B) A gas formed during the reaction
C) A liquid product formed
D) An unreactive compound
E) A catalyst
5. What happens when BaCl₂ reacts with Na₂SO₄?
A) BaSO₄ precipitates out of solution
B) NaCl precipitates
C) No reaction occurs
D) Gas is released
E) Ba and Na combine
6. Which of the following pairs are reactants in a typical double-replacement reaction?
A) Metal + Acid
B) Acid + Base
C) Two ionic compounds in aqueous solution
D) Metal + Oxygen
E) Hydrocarbon + Oxygen
7. In the reaction Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃, what is the precipitate?
A) Pb(NO₃)₂
B) KI
C) PbI₂
D) KNO₃
E) NO₂
8. Which of the following is NOT a typical product of double-replacement reactions?
A) Precipitate
B) Gas
C) Water
D) Elemental metal
E) Aqueous salt solution
9. What role does water play in many double-replacement reactions?
A) It acts as a reactant only
B) It often forms as a product in neutralization reactions
C) It acts as a catalyst
D) It causes decomposition
E) It forms gas bubbles
10. Which double-replacement reaction is an example of neutralization?
A) NaOH + HCl → NaCl + H₂O
B) AgNO₃ + NaCl → AgCl + NaNO₃
C) BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
D) CaCO₃ → CaO + CO₂
E) 2Na + Cl₂ → 2NaCl
11. What is the product when H₂SO₄ reacts with Ba(OH)₂?
A) BaSO₄ + H₂O
B) Ba + SO₄ + H₂O
C) H₂ + BaO + SO₃
D) BaSO₃ + H₂
E) No reaction
12. What does the term "aqueous solution" mean in double-replacement reactions?
A) Reactants are dissolved in water
B) Reactants are gases
C) Reactants are solids only
D) Reactants are liquids only
E) Reactants are melted
13. Which compound usually remains dissolved in solution after a double-replacement reaction?
A) Precipitate
B) Gas
C) Aqueous salt
D) Metal
E) Water
14. Which one of the following reactions produces a gas?
A) NaCl + AgNO₃ → AgCl + NaNO₃
B) CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
C) BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
D) HCl + NaOH → NaCl + H₂O
E) Pb(NO₃)₂ + 2KI → PbI₂ + 2KNO₃
15. Which is a driving force for double-replacement reactions?
A) Formation of a precipitate
B) Increase in temperature
C) High pressure
D) Formation of ions
E) Increase in volume
16. What product forms when Al₂(SO₄)₃ reacts with Ca(OH)₂?
A) CaSO₄ + Al(OH)₃
B) Al₂(OH)₆ + CaSO₄
C) CaSO₄ + Al₂O₃
D) Al₂O₃ + Ca(OH)₂
E) Ca₂SO₄ + AlOH
17. What happens if two aqueous solutions of salts react but no precipitate, gas, or water forms?
A) Double-replacement occurs with gas
B) No reaction occurs
C) Double-replacement with precipitate
D) Neutralization occurs
E) Redox reaction occurs
18. What is the precipitate formed in AgNO₃ + NaCl reaction?
A) NaNO₃
B) AgNO₃
C) NaCl
D) AgCl
E) Cl₂
19. Which of the following is NOT a double-replacement reaction?
A) NaOH + HCl → NaCl + H₂O
B) Zn + HCl → ZnCl₂ + H₂
C) BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
D) Pb(NO₃)₂ + KI → PbI₂ + KNO₃
E) H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O
20. Which is TRUE about double-replacement reactions?
A) They involve exchange of electrons
B) They require oxygen gas
C) They involve exchange of ions between two compounds
D) They always produce gas
E) They involve breaking down compounds into elements
- Questions on Decomposition Reactions
- Question on Combustion Reaction
- Questions on Single-Replacement Reactions
Answers with Explanations
1. B – Two compounds exchange ions to form new compounds.
2. B – Silver nitrate reacts with sodium chloride to form silver chloride precipitate and sodium nitrate.
3. B – A double-replacement reaction generally requires formation of a precipitate, gas, or water to proceed.
4. A – Precipitate is a solid that forms and settles out.
5. A – BaSO₄ is insoluble and precipitates.
6. C – Usually two aqueous ionic compounds exchange ions.
7. C – PbI₂ is the yellow precipitate formed.
8. D – Elemental metals are not formed in double-replacement reactions.
9. B – Water is formed during neutralization reactions (acid + base).
10. A – Acid-base neutralization reaction forming salt and water.
11. A – BaSO₄ precipitate and water form.
12. A – Dissolved in water.
13. C – Salts often remain dissolved as aqueous ions.
14. B – CO₂ gas is formed during acid-carbonate reaction.
15. A – Formation of precipitate drives reaction forward.
16. A – CaSO₄ (soluble) and Al(OH)₃ (precipitate) form.
17. B – If no precipitate, gas, or water forms, no reaction occurs.
18. D – AgCl is the white precipitate.
19. B – Zn + HCl is a single-replacement reaction, not double-replacement.
20. C – Double-replacement involves ion exchange.
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