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.
Test Helpful For:	Chemistry Test ECAT Test MDCAT Test FPSC/PPSC/SPSC/KPPSC/BPSC/AJKPSC/NTS Chemistry Interview Question Answer

Chemistry Chemical Equilibrium Practice Test Online With Explanation

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Page 1 of 3

Chemistry

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

Water evaporates

More water is formed

Equilibrium is not disturbed

More ice is formed

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

High temperature and high pressure

High temperature and low pressure

Low temperature and high pressure

Low temperature and low pressure

3. 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

Common on effect

Le – Chatelier’s principle

Law of mass action

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

Unstable

At very high temperature

Stable

Solids

5. 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

Law of mass action

Le – Chatelier’s principle

Law of conservation of energy

None of all

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

Concentrations of the reactants and products continue to change

Rates of the forward and backward reactions change

Equilibrium constant changes

Reactants and products keep reacting

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

Common ion effect

Dissociation constant for an acid

Dissociation constant

Solubility product

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

Equilibrium will not be formed

Water will evaporate

More water will be formed

More ice will be formed

9. 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, II and III only

I and III only

I and II only

II and III only

10. 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]

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

Impurity

Pressure

Temperature

Concentration

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

Catalyst

Amounts of A₂ and B₂

Temperature

Total pressure

13. What is the relationship between kp and kc?

Kc - kp (RT)∆n

kp = kc (RT)∆n

kc = kp (P)-∆n

kp = kc (RT)-∆n

14. 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

Strong acid and its salt with weak base

Weak base and its salt with strong acid

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

Fast

Slowly

Randomly

Moderately

16. pH of milk is

7.5

6.5

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

0.5

0.25

1.0

3.0

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

Lower side

Optimum side

Constant

Higher side

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

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

The reaction has stopped

Equal volumes of N₂ and H₂ are reacting

Equal masses of N₂ and H₂ are reacting

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

10¯¹⁰

10¯²⁰

10¹⁰

10¯¹⁴

21. Which of the following gives a basic buffer?

NH₄OH + NH₄Cl

NaOH + CH₃ COONa

NaCl + CH₃ COOH

NaOH + NaCl

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

Produce some increase in Kc

Decrease the value of equilibrium constant

Not produce any change in Kc

Double the value of Kc

23. Solubility of any salt can be determined from

Ksp

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

NaCl

Fecl₃₋

Na₂CO₃

Na₂SO₄

25. A basic Buffer solution can be prepared by mixing

Weak base and its salt with strong acid

Weak acid and its slat with strong base

Strong acid and its slat wit weak base

Strong base and its salt with weak acid

Page 2 of 3

26. PH of human blood is

7.00

7.80

7.35

7.50

27. The relationship between Kp and Kc is give by

Kp = Kc (RT)∆

Kc = Kp (RT)∆n

Kp = Kc (RT)-∆n

Kp = Kc (RT)∆n

28. 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

0.0796

1.99

0.0199

0.282

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

Reactant side

Product side

Fluctuate

Remains unchanged

30. Temperature for preparation of SO₃ is

200 °C

400 °C

400 – 500 °C

600 °C

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

7.2 x 10¯⁶

4 x 10¯⁴

3.6 x 10¯⁶

3.6 x 10¯⁵

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

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 will have 50% product and 50% reactant at equilibrium

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

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

0.2 mole of NaCl with 0.2 mole of HNO3

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

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

None of these

Law of Equilibrium

Law of reaction

Law of Mass Action

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

Removal of one of the products regularly

Increase in concentration of one of the reactants

Increase in concentration of one of the products

None of these

36. Which pH is considered as basic?

37. Who studied the effect of temperature on equilibrium?

Vant Hoff

Van der Waal

Lewis

Arrhenius

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

Equal to 7

More than 7

No effect

Less than 7

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

K = 10³

K = 10

K = 10¯²

K = 10⁰

40. The state of equilibrium refers to

State or rest

Stationary state

Dynamic state

State of inertness

41. Reaction which proceed in both the directions is called

Non spontaneous

Irreversible

Spontaneous

Reversible

42. A buffer solution can be prepared by mixing

A weak acid and weak base

A strong acid and weak base

A strong acid and its salt

A weak base and its salt with strong acid

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

Conversion of A to B is only 50% complete

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

Complete conversion of A to B has taken place

Only 10% conversion of A to B has taken place

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

Be halved

Remains the same

Also be doubled

Becomes one fourth

45. 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

Is not characteristic of the reaction

Depends on the concentration of one of the products at equilibrium

46. Conjugate base of a very weak acid is

Do not ionize

Weak base

Strong base

Salt

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

Law of mass action

All of these

Law of active mass

Law of mobile equilibrium

48. 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

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

Pressure

Catalyst

None of these

Temperature

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

None of all

Static equilibrium

Chemical equilibrium

Dynamic equilibrium

Page 3 of 3

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

Favour the decomposition of N₂O₄

Not alter the equilibrium

Favour the formation of N₂O₄

Stop the reaction

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

Blood

Solution of CuSO4

Brine

Glue

53. Idea of PH and POH was put forward by

Gibbs

Einstein

Sorenson

Chadwiick

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

Strong acid and strong base

Weak base and its salt with a strong acid

Weak acid and its salt with a strong base

Weak acid and strong base

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

Equilibrium will established

Reaction goes forward

Reaction stops after some time

Reaction goes backward

56. Which of the following is more acidic?

Bread

Apples

Bananas

Lemons

57. Kc > Products / Reactants favours

Equilibrium

Backward reaction

Reaction completed

Forward reaction

58. Addition of CH3COOH and CH3COONa gives in water

Standard solution

Buffer solution

Both b and c

Acidic buffer solution

59. 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

0.02

0.2

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

Decomposition Reaction

Constant Reaction

Irreversible Reaction

Reversible Reaction

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

None of these

The reaction stops completely

HI dissociation stops

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

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

None

Individually

Simultaneously

Both a and b

63. Units of Kc is

Moles¯² dm⁺⁶

Moles² dm⁺⁶

Kc may or may not have units

Moles⁺² dm¯⁶

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Malik TahirLast Updated: October 14, 2025

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