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Chemistry Chemical Equilibrium Online Mcqs Test

Malik TahirLast Updated: October 14, 2025

Important Chemistry Chemical Equilibrium Question and Answer

Total Questions:	63
Time Allowed:	30 Minutes
Total Marks:	63
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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Chemistry Chemical Equilibrium Practice Test Online With Explanation

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Page 1 of 3

Chemistry

1. Two moles of HI was heated in a sealed tube at 440°C till the equilibrium was reached. HI was found to be 22% decomposed. The equilibrium constant for dissociation is

0.282

0.0796

0.0199

1.99

2. In an exothermic reversible reaction increase in temp shifts the equilibrium to

Fluctuate

Remains unchanged

Product side

Reactant side

3. PH of human blood is

7.00

7.35

7.50

7.80

4. Le-Chatelier’s principle is sometime known as

All of these

Law of mobile equilibrium

Law of mass action

Law of active mass

5. Temperature for preparation of SO₃ is

200 °C

600 °C

400 – 500 °C

400 °C

6. When rate of forward reaction is equal to rate of backward reaction, then the equilibrium established is called

None of all

Chemical equilibrium

Static equilibrium

Dynamic equilibrium

7. AgCl dissolved with cone (2 x 10¯²) Ksp will be

3.6 x 10¯⁶

7.2 x 10¯⁶

3.6 x 10¯⁵

4 x 10¯⁴

8. For a reaction H₂ + I₂ ⇌ 2HI at 721 K, the value of equilibrium constant is 50. If 0.5 moles each of H₂ and I₂ is added to the system the value of equilibrium constant will be

0.2

0.02

9. Which set of solutes will form a buffer when dissolved in water to make 1 litter of solution?

0.4 mole of NH3 with 0.2 mole of HCl

0.4 mole of CH3COOH with 0.4 mole of NaOH

0.0002M HCl

0.2 mole of NaCl with 0.2 mole of HNO3

10. A basic Buffer solution can be prepared by mixing

Weak base and its salt with strong acid

Strong acid and its slat wit weak base

Weak acid and its slat with strong base

Strong base and its salt with weak acid

11. Which of the following is more acidic?

Apples

Bread

Lemons

Bananas

12. pH of milk is

6.5

7.5

13. The equilibrium constant in a reversible chemical reaction at a given temperature

Depends on the initial concentration of the reactants

Does not depend on the initial concentrations of reactants

Depends on the concentration of one of the products at equilibrium

Is not characteristic of the reaction

14. Synthesis of ammonia by Habor process is an example of ___________

Constant Reaction

Reversible Reaction

Irreversible Reaction

Decomposition Reaction

15. The state of equilibrium refers to

Dynamic state

Stationary state

State of inertness

State or rest

16. Addition of CH3COOH and CH3COONa gives in water

Standard solution

Acidic buffer solution

Buffer solution

Both b and c

17. An equilibrium constant of 10¯⁴ for a reaction means that the reaction is

One that will have 50% product and 50% reactant at equilibrium

One that is very favorable and will have mostly product at equilibrium

The equilibrium constant only relates to the speed of a reaction and not to the amount of product formed

One that is unfavourable and will not have very much product at equilibrium

18. Kc > Products / Reactants favours

Reaction completed

Backward reaction

Forward reaction

Equilibrium

19. If rate of concentration of reaction is equal to rate of concentration of products in reversible reaction the __________

Equilibrium will established

Reaction stops after some time

Reaction goes forward

Reaction goes backward

20. If the value of kc is very low then the forward reaction will occur __________

Slowly

Fast

Moderately

Randomly

21. Units of Kc is

Moles¯² dm⁺⁶

Kc may or may not have units

Moles² dm⁺⁶

Moles⁺² dm¯⁶

22. Preparation of buffer solution can be done by mixing

Weak acid and its salt with weak base

Strong base and its salt with weak acid

Weak base and its salt with strong acid

Strong acid and its salt with weak base

23. In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled then the equilibrium constant will

Also be doubled

Remains the same

Becomes one fourth

Be halved

24. By the addition of base in water pH will be

Equal to 7

More than 7

No effect

Less than 7

25. Solubility of any salt can be determined from

Ksp

Page 2 of 3

26. The factor which changes equilibrium constant o the reaction A₂(g) + B₂(g) → 2 AB(g) is

Temperature

Amounts of A₂ and B₂

Total pressure

Catalyst

27. Idea of PH and POH was put forward by

Sorenson

Chadwiick

Einstein

Gibbs

28. What is the relationship between kp and kc?

Kc - kp (RT)∆n

kp = kc (RT)∆n

kc = kp (P)-∆n

kp = kc (RT)-∆n

29. A buffer solution can be prepared by mixing

A strong acid and weak base

A weak base and its salt with strong acid

A weak acid and weak base

A strong acid and its salt

30. When ever a week a base is dissolved in water, it gives its conjugate acid similarly a weal acid in water products its conjugate base. The conjugate acid base pair is stated by

Lowery Bronsted concept

Le – Chatelier’s principle

Law of mass action

Common on effect

31. When sparingly soluble salt is in equilibrium with molar concentration of its oppositely charged ion when the product is called

Dissociation constant

Dissociation constant for an acid

Common ion effect

Solubility product

32. When pressure is applied to the equilibrium system Ice ⇌ Water? Which of the following phenomenon will happen?

More ice will be formed

Water will evaporate

Equilibrium will not be formed

More water will be formed

33. Which of the following gives a basic buffer?

NaOH + NaCl

NaCl + CH₃ COOH

NH₄OH + NH₄Cl

NaOH + CH₃ COONa

34. The reaction 2SO₂ + 2O₂ ⇌ 2SO will be favoured by

Low temperature and high pressure

High temperature and low pressure

High temperature and high pressure

Low temperature and low pressure

35. The product of [0H¯][H⁺] at 25C° is

10¹⁰

10¯¹⁰

10¯¹⁴

10¯²⁰

36. In reversible reaction the changes in forward and backward reaction occur _________

Both a and b

Individually

Simultaneously

None

37. Which of the following aqeous solution will be basic?

NaCl

Fecl₃₋

Na₂SO₄

Na₂CO₃

38. When H₂ and I₂ are mixed and equilibrium is attained, then

None of these

Amount of HI formed is equal to the amount of H₂ dissociated

HI dissociation stops

The reaction stops completely

39. What can affect the magnitude of equilibrium constant Kp of a reversible gaseous reaction

Pressure

Catalyst

Temperature

None of these

40. Chemical equilibrium is referred to as dynamic because, at equilibrium, the

Rates of the forward and backward reactions change

Concentrations of the reactants and products continue to change

Equilibrium constant changes

Reactants and products keep reacting

41. At start of reaction, concentration of reactants are on

Lower side

Constant

Optimum side

Higher side

42. For the reaction 2A(g) + B(g) ⇌ 3C(g) + D(g) two moles each of A and B were taken into a flask. The following must always be true when the system attained equilibrium

[B] = [C]

[A] > [C]

[A] < [B]

[A] = [B]

43. Reaction which proceed in both the directions is called

Irreversible

Reversible

Non spontaneous

Spontaneous

44. When pressure is applied to the given equilibrium ice water which of the following will happen

More water will be formed

Water will formed

More ice will be formed

Equilibrium will not be disturbed

45. Which pH is considered as basic?

46. Water and ice are in equilibrium at 0C° and pressure is applied at this stage, then

More water is formed

Water evaporates

More ice is formed

Equilibrium is not disturbed

47. If a buffer solution of higher PH than seven is to be made we use

Strong acid and strong base

Weak acid and strong base

Weak base and its salt with a strong acid

Weak acid and its salt with a strong base

48. The rate at which a substance reacts is directly proportional to its active mass and the rate of reaction is directly proportional to the product of the active mass of reacting substances is known as

None of all

Le – Chatelier’s principle

Law of mass action

Law of conservation of energy

49. At certain temperature, 50% of HI is dissociated into H₂ and I₂ the equilibrium constant is

0.25

3.0

0.5

1.0

50. In an exothermic reaction, a 10° rise in temperature will

Double the value of Kc

Produce some increase in Kc

Decrease the value of equilibrium constant

Not produce any change in Kc

Page 3 of 3

51. The relationship between Kp and Kc is give by

Kp = Kc (RT)-∆n

Kc = Kp (RT)∆n

Kp = Kc (RT)∆n

Kp = Kc (RT)∆

52. In which of the following cases, the reaction goes farthest to completion?

K = 10³

K = 10⁰

K = 10¯²

K = 10

53. The rate of chemical reaction is directly proportional to the active mass of reactant this statement is known as ___________

Law of Equilibrium

Law of reaction

None of these

Law of Mass Action

54. A chemical reaction A ⇌ B is said to be in equilibrium when

The rate of transformation of A to B is just equal to rate of transformation of B to A in the system.

Conversion of A to B is only 50% complete

Complete conversion of A to B has taken place

Only 10% conversion of A to B has taken place

55. Who studied the effect of temperature on equilibrium?

Lewis

Vant Hoff

Van der Waal

Arrhenius

56. For equilibrium 2NO₂(g) ⇌ N₂O₄(g) + 14.6 kcal increase of temperature would

Favour the formation of N₂O₄

Favour the decomposition of N₂O₄

Stop the reaction

Not alter the equilibrium

57. Which statements are correct for a reaction at equilibrium?
(I) The forward and reverse reactions both continue
(II) The rates of the forward and reverse reactions are equal
(III) The concentrations of reactants and products are equal

I and II only

I and III only

II and III only

I, II and III only

58. Conjugate base of a very weak acid is

Strong base

Do not ionize

Salt

Weak base

59. In a chemical reaction N₂ + 3H₂ ⇌ 2NH₃ at equilibrium point

The reaction has stopped

Equal masses of N₂ and H₂ are reacting

The same amount of ammonia is formed as is decomposed into N₂ and H₂

Equal volumes of N₂ and H₂ are reacting

60. Which of the following factors will favour the reverse reaction in a chemical equilibrium?

Increase in concentration of one of the reactants

Increase in concentration of one of the products

None of these

Removal of one of the products regularly

61. In reversible reactions, if the forward reaction occur very fast then reactant (s) is (are) __________

Unstable

Solids

Stable

At very high temperature

62. Which one of the following is a buffer solution?

Glue

Solution of CuSO4

Brine

Blood

63. The equilibrium will shift towards right by increasing ___________ of reactants

Pressure

Concentration

Impurity

Temperature

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Malik TahirLast Updated: October 14, 2025

Chemistry Chemical Equilibrium Online Mcqs Test

Important Chemistry Chemical Equilibrium Question and Answer

Chemistry Chemical Equilibrium Practice Test Online With Explanation

Chemistry

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