Chem – Chapter 6: Equilibria

1

According to Le Chatelier's principle, decreasing the concentration of a product will:

A Shift equilibrium to the left B Shift equilibrium to the right C Have no effect D Increase the equilibrium constant

2

For an exothermic reversible reaction at equilibrium, increasing the temperature will:

A Shift the equilibrium to the right B Shift the equilibrium to the left C Increase both forward and backward rates equally D Have no effect on equilibrium

3

Which of the following is true about an irreversible reaction?

A It reaches equilibrium B It goes to completion C It is represented by a double arrow D It can be reversed easily

4

For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what is the effect of increasing pressure on the equilibrium?

A It shifts to the left. B It shifts to the right. C It has no effect. D It changes the equilibrium constant.

5

A closed system is necessary for dynamic equilibrium because:

A reactants cannot be added B products cannot be removed C matter cannot enter or leave D temperature remains constant

6

Increasing the concentration of a reactant in an equilibrium mixture will:

A shift equilibrium to the right B shift equilibrium to the left C stop the forward reaction D have no effect on equilibrium

7

According to Le Chatelier's principle, what happens when the pressure is increased on a gaseous equilibrium?

A The equilibrium shifts to the side with fewer moles of gas. B The equilibrium shifts to the side with more moles of gas. C The equilibrium constant always increases. D The reaction stops.

8

ایک خارجی حرارت والے قابلِ برگشت عمل میں درجہ حرارت بڑھانے سے توازن کس طرف منتقل ہوگا؟

A آگے کی طرف B پیچھے کی طرف C کوئی منتقلی نہیں D دونوں طرف برابر

9

The value of the equilibrium constant K depends on:

A Initial concentrations B Temperature C Pressure D Volume

10

The equilibrium constant Kc depends on:

A temperature B pressure C catalyst D volume of container

11

According to Le Chatelier's principle, what happens when the pressure is increased on a gaseous equilibrium involving fewer moles of gas on the product side?

A Equilibrium shifts to the side with more moles of gas B Equilibrium shifts to the side with fewer moles of gas C Equilibrium remains unchanged D The reaction stops

12

What is the role of a catalyst in a reversible reaction at equilibrium?

A It increases the rate of both forward and backward reactions equally. B It shifts the equilibrium to the forward direction. C It shifts the equilibrium to the backward direction. D It changes the value of the equilibrium constant.

13

Which of the following is a characteristic of a reversible reaction?

A It goes to completion only. B It can proceed in both forward and backward directions. C It stops when reactants are used up. D It never reaches equilibrium.

14

In a closed system at equilibrium, which statement is correct?

A The forward reaction has stopped completely B The rate of the forward reaction equals the rate of the reverse reaction C The concentration of products keeps increasing D Only the reverse reaction takes place

15

What is the effect of increasing the concentration of a reactant on the equilibrium position?

A Shifts equilibrium to the left B Shifts equilibrium to the right C No effect on equilibrium D Stops the reaction

16

For an endothermic reaction at equilibrium, increasing temperature will:

A shift equilibrium in the forward direction B shift equilibrium in the backward direction C decrease the value of Kc D not affect the equilibrium

17

According to Le Chatelier's principle, if the concentration of a product is decreased, the equilibrium shifts:

A To the left B To the right C No shift D Becomes unpredictable

18

Which statement about a reversible reaction at equilibrium is correct?

A The forward reaction has stopped. B The backward reaction has stopped. C Both forward and backward reactions occur at equal rates. D The concentrations of reactants and products become equal.

19

Which statement about a system at equilibrium is correct?

A The reaction has stopped. B The forward and backward reactions continue at equal rates. C The concentration of reactants is zero. D The equilibrium constant is zero.

20

Which statement about a reversible reaction is correct?

A It can proceed in both forward and backward directions. B It goes only to completion. C It never reaches equilibrium. D It uses a single arrow.

21

At equilibrium, if the value of Kc is very large, it means:

A Reactants are favoured B Products are favoured C Reaction is at equilibrium with equal amounts D Reaction is irreversible

22

According to Le Chatelier's principle, increasing the concentration of a reactant will:

A Shift equilibrium to the left B Shift equilibrium to the right C Have no effect on equilibrium D Stop the reaction

23

The equilibrium constant expression for the reaction aA + bB ⇌ cC + dD is:

A [C]^c [D]^d / [A]^a [B]^b B [A]^a [B]^b / [C]^c [D]^d C [C][D] / [A][B] D [A][B] / [C][D]

24

Which of the following reactions is irreversible?

A Formation of ammonia from nitrogen and hydrogen B Combustion of methane in oxygen C Dissolution of carbon dioxide in water D Decomposition of calcium carbonate in a closed container

25

Dynamic equilibrium is established in a closed system when:

A forward reaction stops B backward reaction stops C forward and backward rates become equal D concentrations of reactants become zero