Chemistry Class 10 Chapter 9 Important MCQs Federal Board

Class 10^th Chemistry Notes

Chemical Equilibrium mcqs

Multiple Choice Questions:

The reversible reaction is shown by

Single-headed arrow
Double-headed arrow
By single and double-headed both
None of the above

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2. The irreversible reaction is shown by

Single-headed arrow
Double-headed arrow
By single and double-headed both
None of the above

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3. The reaction in which the reactants are completely consumed and formed products and no amount of reactants left behind are called.

Reversible reaction
Irreversible reaction
Forward reaction
None of these

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4. The reaction in which products react and go in a backward direction and yield reactants again is called

Reversible reaction
Irreversible reaction
Complete reaction
Both a and c

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5. The law of mass action was proposed by

Charles
P. Waage
C.M Gulberg
Both b and c

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6. Which of the following reaction helps to achieve dynamic equilibrium

Irreversible reaction
Reversible reaction
Both a and b
Chemical reaction

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7. When the rate of forward reaction becomes equal to the rate of backward reaction then this state is called:

Chemical equilibrium
Stable equilibrium
Unstable equilibrium
Both a and b

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8. The product of the ratio of forward reaction and reverse reaction is called:

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9. The proportionality constant for forward reaction is :

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10. The proportionality constant of reverse reaction is:

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11.Active mass represents the :

Molar concentration of reactants
Reactants and products temperature
Reactants and products pressure
Reactants and products volume

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12.Active Mass of substance is _________ in a dilute solution

KJ
mol/dm3
g/liter
Coulomb

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13. The concentration of reactants and products can be expressed in terms of:

( )
[ ]
{ }
None of the above

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14. In Kc the small c denotes

Direction
Molar concentration
Coefficient
Both a and c

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15. Kc depends upon the :

Temperature
Pressure
Volume
None of the above

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16.On the initial concentration of reactants and products, one constant is independent:

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17. Which of the following is not determined by Kc

Chemical reaction’s direction
Chemical reaction’s extent
Equilibrium’s mixture concentration when the initial concentration of reactants is known
Catalyst used in a reaction

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18. The process by which ammonia is synthesized is called

Contact process
Haber process
Titration
Spectroscopy

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19.The process by which sulfuric acid is synthesized is called

Contact process
Haber process
Titration
Spectroscopy

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20.Le Chatellier’s principle is used to

Increase the yield of product
Increase the yield of reactants
Decrease the yield of product
Decrease the yield of reactants

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21. Name the catalyst used for the synthesis of ammonia is

V₂O₅
Fe
Ni
Pt

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22.Name the catalyst used in the below reaction

V₂O₅
Fe
Ni
Pt

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23. The temperature used in the Haber process is :

400 ^oC
500 ^oC
450 ^oC
600 ^oC

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24. The temperature used in the formation of sulfur-trioxide is

400 ^oC
500 ^oC
450 ^oC
600 ^oC

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25. The pressure used in the Haber process is

300 atm
200 atm
250 atm
350 atm

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26. The gas which is dissolved in fizzy drinks under high pressure is:

O₂
CO₂
N₂
CO

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27.The pressure used in the formation of SO₃ is:

100 atm
200 atm
300 atm
400 atm

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28.The percentage of ammonia and sulfuric acid produced by Le Chatellier’s principle is:

80 % yield
85 % yield
90 % yield
98 % yield

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29.Law of mass action is directly proportional to the product of active masses of:

Reactants
Products
Both a and b
None of the above

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30.The expression of Kc for the below reaction will be

[N₂] [H₂]³ / [NH₃]²
[NH₃]² [N₂] / [H₂]³
[NH₃]² / [N₂] [H₂]³
[NH₃]² [H₂]³ / [N₂]

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31.The unit of Kc for the below reaction will be

mol^-1.dm³
mol² / dm⁶
dm³ / mol
mol / dm³

Solution:

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32.For which of the following reaction the Kc will have no unit

Solution for first reaction: Solution for second reaction:

When two moles of product and three moles of reactants are combined in the first reaction, one mole of reactant will remain, and this remaining mole will be the unit of Kc.

Two moles of product will cancel with two moles of reactants in the second reaction since there are two moles of reactants and four moles of reactants, and the remaining two moles of reactants will be left behind and create the unit of Kc.

Solution for third reaction: Solution for fourth reaction:

There will be no unit of Kc since there are two moles of products and two moles of reactants in the third reaction, cancelling each other out and leaving nothing behind.

One mole of the product will cancel with one mole of reactant in the fourth reaction since there are two moles of reactants and one mole of product. The remaining mole of reactant will be the unit of Kc.

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33. Which of the following reaction is reversible

According to the reactions, reaction 3 is reversible because there is a double-headed arrow between the reactants and products, whereas the other reactions are irreversible since there is only a single-headed arrow between the reactants and products.

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34. Which of the following reaction is irreversible

Solution: We can see from the reaction arrows that reaction one is represented by a single-headed arrow, and we are aware that a single-headed arrow signifies an irreversible reaction. Reaction 1 is hence irreversible. While reactions 2, 3, and 4 are reversible, as seen from the double-headed arrows used to symbolise them.

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35.Initially when the reaction starts then the rate of reverse reaction will be:

High
Low
Zero
None of the above

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36.Initially when the reaction starts then the rate of forwarding reaction will be:

Highest
Lowest
Zero
Both b and c

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37.When evaporation and condensation rates become equal then it means that the system is in a state of:

Equilibrium
Unstable
Stable
Neutral

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38.The below reaction takes place in the presence of which one catalyst?

Fe
V₂O₅
Electric spark
Ni

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39.

[ ] ^a [ ] ^b the a and b in the superscript on the square bracket represent the
Number of moles of reactants
Number of moles of products
Both a and b
None of the above

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40.The unit of Kc for the below reaction will be

mol^-1.dm³
mol/dm³
mol²/dm^-6
None of the above

Solution:

Given that there are two moles of products and one mole of reactant in this reaction, one mole of the product will cancel out with one mole of reactant, leaving the other mole of product—which corresponds to the unit of Kc—behind.

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41.Which statement is true about the state of equilibrium?

Forward reaction stops
Reverse reaction stops
Forward and reverse both reactions stop
Both forward and reverse reactions continue at the same rate

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42. When a mixture of H₂ and I₂ is sealed in a flask and the temperature is kept at 25 ^oC, the following equilibrium is established.

Which substance will be present in the equilibrium mixture?

H₂ and I₂
HI only
H₂ only
H₂ , I₂ and HI

The reaction can go either way since it is reversible, and we know that reversible reactions can go both ways. Therefore, equilibrium will be reached once the rates of forward and reverse reactions are equal. At this point, the concentrations of the reactants and products will be equal. As a result, the equilibrium mixture will contain both the reactants (H₂, I₂) and the product (HI) at the same concentration.

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43.Derive the Kc unit for

mol^-1.dm³
mol² / dm⁶
dm³ / mol
No unit

Solution:

We can see that there are two moles of products and three moles of reactants in this reaction. As a result, one mole of reactant will be left behind after cutting two moles of reactants into two moles of products, and this will serve as the unit of Kc.

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44. For which of the following reactions Kc will have unit less?

1
2
3
All of the above

Solution:

Because there are the same amounts of reactants and products in each of the three reactions, they all cancel one another out and leave no remaining unit for Kc.

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45. The concentration of reactants and products at equilibrium remains unchanged if :

Concentration of any reactant or product is not changed
Temperature of the reaction is not changed
Pressure or volume of the system is not changed
All of the above are observed

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46. Which of the following does not happen when a system is at an equilibrium state?

Forward and reverse reactions stop
Forward and reverse reaction rates become equal
Reactants and products concentration stops changing
Reaction occur in both the directions

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47. For which one reaction the unit of Kc will be mol/dm³

Solution:

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48. How equilibrium is established, in an irreversible reaction :

Established quickly
Established slowly
Never established
Established when reaction stops

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49. Active mass can be justified as :

Total mass of the reactants
Total mass of products
Total mass of reactants and products
Mass of substance in mole per dm³ in a dilute solution

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50. For a reverse reaction

Which substance is the product of the reaction?

A
B
Both A and B
C

Solution: We know that Kc is the product of the ratio of products and reactant concentration in light of the law of mass action. Thus, [C]² is the result (product).