Questions on Nonreversible Reactions
Multiple-Choice Questions: Nonreversible Reactions
1. What is a nonreversible reaction?
A) A reaction that reaches equilibrium
B) A reaction that occurs only in the reverse direction
C) A reaction that proceeds in one direction and cannot easily go backward
D) A reaction that never finishes
E) A reaction that uses a catalyst
2. Which of the following best represents a nonreversible reaction?
A) ⇌
B) →
C) ←
D) =
E) ⇋
3. Which condition favors a nonreversible reaction?
A) A closed container
B) Equal rates of forward and reverse reactions
C) The complete removal of one or more products
D) Constant temperature
E) A catalyst added
4. Which of the following is usually nonreversible under normal conditions?
A) H₂O ⇌ H⁺ + OH⁻
B) N₂ + 3H₂ ⇌ 2NH₃
C) Combustion of methane
D) Decomposition of calcium carbonate
E) Dissolution of table salt in water
5. Nonreversible reactions often result in:
A) Products that readily recombine
B) No change in energy
C) Complete conversion of reactants to products
D) Establishment of dynamic equilibrium
E) No formation of products
6. Which of the following is a hallmark of a nonreversible reaction?
A) Products are unstable
B) Reactants remain unchanged
C) One or more products are removed or escape the system
D) Products and reactants are in balance
E) It proceeds indefinitely
7. Which of the following is most likely to represent a nonreversible reaction in a biological system?
A) Enzyme-substrate binding
B) DNA replication
C) ATP hydrolysis
D) Photosynthesis
E) Protein folding
8. Combustion reactions are classified as nonreversible because:
A) They use water
B) They occur only at low temperature
C) The reverse reaction is highly unfavorable
D) They involve weak acids
E) They require sunlight
9. A reaction that produces a gas which escapes is often:
A) An equilibrium reaction
B) A nonspontaneous reaction
C) A nonreversible reaction
D) A neutralization reaction
E) A photochemical reaction
10. Which of the following situations will make a reversible reaction effectively nonreversible?
A) Keeping products in solution
B) Isolating products immediately
C) Lowering pressure
D) Decreasing temperature
E) Adding more catalyst
11. Why are precipitation reactions typically considered nonreversible?
A) Because they involve color change
B) Because solids do not dissolve back under the same conditions
C) Because they are exothermic
D) Because they require energy input
E) Because they produce gas
12. What makes the reverse of a nonreversible reaction difficult?
A) The reverse rate is faster
B) It violates the law of conservation
C) The energy barrier is too high or products are too stable
D) There is no change in concentration
E) It occurs in an open system
13. Which of these is NOT a common characteristic of nonreversible reactions?
A) Release of gas
B) Formation of a precipitate
C) Large equilibrium constant
D) Establishment of dynamic equilibrium
E) Strongly exothermic or endothermic behavior
14. Which chemical change is most likely nonreversible?
A) Ice melting
B) Boiling water
C) Rusting of iron
D) Condensation of vapor
E) Dissolving sugar
15. A nonreversible reaction generally:
A) Has equal forward and reverse rates
B) Involves unstable products
C) Has no net change in reactants and products
D) Has a very large or very small K_eq
E) Stops after a few minutes
16. Which is a correct example of a nonreversible reaction?
A) CO₂ ⇌ CO + ½O₂
B) H₂O ⇌ H⁺ + OH⁻
C) NaOH + HCl → NaCl + H₂O
D) NH₃ + H₂O ⇌ NH₄⁺ + OH⁻
E) N₂ + O₂ ⇌ 2NO
17. Which condition can help convert a potentially reversible reaction into a nonreversible one?
A) Increasing the concentration of products
B) Performing the reaction in an open container where gas escapes
C) Adding more reactant continuously
D) Stirring the reaction constantly
E) Removing the catalyst
18. In a chemical reaction, the formation of a stable covalent compound often leads to:
A) Reversible behavior
B) Nonreversible reaction
C) Instant equilibrium
D) Formation of radicals
E) Energy absorption
19. Which factor does NOT contribute to a reaction being nonreversible?
A) Formation of gas
B) Formation of an insoluble solid
C) High activation energy for the reverse reaction
D) Equal concentrations of products and reactants
E) Removal of products
20. Which of the following is true for all nonreversible reactions?
A) They can be reversed in a laboratory
B) They never involve gases
C) They proceed until the limiting reactant is used up
D) They occur only in living organisms
E) They always require catalysts
- Questions on Reversible Reaction
- Questions on Chemical Equilibrium
- Questions on Equilibrium Constant (K_eq) and Calculations
Answer Key with Explanations
1. C – A nonreversible reaction proceeds only in one direction, with no significant reverse reaction.
2. B – The single arrow (→) denotes a one-way, nonreversible reaction.
3. C – Removing products shifts the reaction irreversibly forward.
4. C – Combustion reactions release energy and are effectively irreversible.
5. C – In nonreversible reactions, reactants are fully converted into products.
6. C – Product escape (e.g., gas release) prevents the reverse reaction.
7. C – ATP hydrolysis is a key nonreversible biochemical reaction.
8. C – The reverse of combustion is thermodynamically unfavorable.
9. C – Gas escapes mean the system cannot re-establish equilibrium easily.
10. B – Isolating or removing products prevents the reverse reaction.
11. B – Precipitates typically don’t redissolve under the same conditions.
12. C – High energy barriers or stable products prevent reverse reactions.
13. D – Dynamic equilibrium is not characteristic of nonreversible reactions.
14. C – Rusting is a chemical change and nonreversible under normal conditions.
15. D – Very large or very small K_eq values indicate a one-directional reaction.
16. C – Neutralization reactions (acid + base → salt + water) are nonreversible.
17. B – An open container lets gas escape, preventing the reverse reaction.
18. B – Stable compounds mean the reverse reaction is less likely to occur.
19. D – Equal concentrations suggest equilibrium, not a nonreversible reaction.
20. C – Nonreversible reactions go to completion, stopping when reactants run out.
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