Important MCQs Related to REVERSIBLE REACTION AND DYNAMIC EQUILIBRIUM || 10th Chemistry
1. What are the substances that combine in a chemical reaction called?
A) Products
B) Reactants
C) Catalysts
D) Inhibitors
2. What is the new substance formed in a chemical reaction called?
A) Reactant
B) Catalyst
C) Product
D) Solvent
3. What type of reaction is represented by a single arrow?
A) Reversible
B) Irreversible
C) Dynamic
D) Equilibrium
4. What type of reaction never goes to completion?
A) Irreversible
B) Combustion
C) Reversible
D) Decomposition
5. How are reversible reactions represented?
A) Single arrow
B) No arrow
C) Double arrow
D) Curved arrow
6. In which type of reaction do products recombine to form reactants?
A) Irreversible
B) Reversible
C) Decomposition
D) Substitution
7. What is the direction of the forward reaction?
A) Left to right
B) Right to left
C) Top to bottom
D) Bottom to top
8. What happens to iodine’s purple color when it forms hydrogen iodide?
A) It turns red
B) It fades
C) It darkens
D) It remains the same
9. What is formed when hydrogen iodide is heated?
A) Hydrogen and water
B) Hydrogen and iodine
C) Oxygen and water
D) Nitrogen and oxygen
10. What type of reaction produces hydrogen and iodine from hydrogen iodide?
A) Forward reaction
B) Irreversible reaction
C) Reverse reaction
D) Substitution reaction
11. What is dynamic equilibrium?
A) Reaction stops completely
B) Reaction proceeds only forward
C) Reaction continues with equal rates in both directions
D) Reaction reverses only
12. What type of equilibrium occurs when a building remains standing?
A) Dynamic equilibrium
B) Static equilibrium
C) Chemical equilibrium
D) Physical equilibrium
13. What happens to the forward reaction rate as a reversible reaction proceeds?
A) It increases
B) It remains constant
C) It slows down
D) It stops
14. In dynamic equilibrium, what happens to the concentration of reactants and products?
A) Increases
B) Decreases
C) Remains constant
D) Disappears
15. What must be true for an equilibrium to be achieved?
A) It must be an open system
B) It must be a closed system
C) It must have a catalyst
D) It must have high pressure
16. What is the rate of the forward reaction at the beginning of a reversible reaction?
A) Very slow
B) Very fast
C) Negligible
D) Constant
17. At equilibrium, what is the relationship between the forward and reverse reaction rates?
A) Forward is faster
B) Reverse is faster
C) Both are equal
D) Both are zero
18. What is the reverse reaction’s direction?
A) Left to right
B) Right to left
C) Top to bottom
D) Bottom to top
19. What happens when calcium carbonate is heated in an open flask?
A) It forms calcium oxide and CO₂
B) It remains unchanged
C) It dissolves
D) It reacts with water
20. What is the initial state of the reverse reaction in a dynamic equilibrium?
A) Very fast
B) Negligible
C) Constant
D) Complete
21. What does the double arrow (↔) represent in chemical reactions?
A) Static equilibrium
B) Irreversible reaction
C) Reversible reaction
D) Completed reaction
22. Which reaction occurs from right to left?
A) Forward reaction
B) Reverse reaction
C) Irreversible reaction
D) Combination reaction
23. When is the rate of the reverse reaction negligible?
A) At the beginning
B) At equilibrium
C) At the end
D) Throughout the reaction
24. What happens to physical properties at equilibrium?
A) They change constantly
B) They remain the same
C) They increase
D) They decrease
25. What type of reaction forms products from reactants?
A) Reverse reaction
B) Forward reaction
C) Static reaction
D) Decomposition reaction
26. What must be true for a reaction to be reversible?
A) It must be in an open system
B) It must go to completion
C) It must proceed in both directions
D) It must stop completely
27. What happens to the rate of forward reaction as products increase?
A) It increases
B) It decreases
C) It remains constant
D) It stops
28. What happens to calcium oxide and CO₂ in a closed flask during heating?
A) They decompose
B) They react to form calcium carbonate
C) They evaporate
D) They remain unchanged
29. Which type of equilibrium occurs when a reaction’s rates are balanced but the reaction continues?
A) Static equilibrium
B) Dynamic equilibrium
C) Irreversible equilibrium
D) Physical equilibrium
30. In dynamic equilibrium, what remains constant besides the concentration of reactants and products?
A) Reaction speed
B) Colour and density
C) Amount of energy
D) Pressure and volume