Chem – Chapter 5 + Chapter 6

1

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

2

For the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), increasing the pressure will:

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

3

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

4

In human muscles, anaerobic respiration produces:

A Ethanol and CO₂ B Lactic acid C CO₂ and H₂O D Glucose

5

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

A shift the equilibrium to the backward direction B shift the equilibrium to the forward direction C increase the value of Kc D have no effect on the equilibrium

6

In a closed system, which of the following is a characteristic of dynamic equilibrium?

A Reactants are completely converted to products B Both forward and reverse reactions continue at equal rates C The reaction stops D Only the forward reaction occurs

7

A reversible reaction can reach equilibrium only if it takes place in a:

A Open system B Closed system C Vacuum D Catalyst

8

What is the main product of anaerobic respiration in yeast?

A Carbon dioxide and water B Lactic acid C Ethanol and carbon dioxide D Glucose and oxygen

9

Anaerobic respiration in human muscles produces:

A Ethanol and CO2 B Lactic acid C CO2 and H2O D Glucose and O2

10

The transition state in a reaction is also known as:

A Activated complex B Product C Catalyst D Intermediate

11

The enthalpy change (ΔH) of a reaction is measured using a:

A Thermometer B Calorimeter C Barometer D Hydrometer

12

According to collision theory, a reaction takes place when reactant particles:

A Collide with sufficient energy B Are heated only C Are kept in a closed container D Change their shape

13

Which statement is true about the equilibrium constant Kc?

A It depends on initial concentrations. B It changes with the addition of a catalyst. C It is constant at a given temperature. D It changes with pressure for all reactions.

14

What is the main role of a catalyst in a chemical reaction?

A It increases the activation energy B It decreases the activation energy C It is consumed in the reaction D It changes the products formed

15

In an exothermic reaction, what happens to the enthalpy change (ΔH)?

A It is positive because heat is absorbed B It is negative because heat is released C It is zero because no heat is exchanged D It becomes undefined

16

In the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), increasing pressure will shift equilibrium:

A towards NH3 (fewer gas molecules) B towards N2 and H2 (more gas molecules) C no shift at all D towards both sides equally

17

Which of the following is an isolated system?

A A sealed thermos flask B A cup of hot tea C A boiling pot without lid D An open beaker

18

Which of the following is an exothermic reaction?

A Melting of ice B Combustion of methane C Evaporation of water D Photosynthesis

19

According to Le Chatelier's principle, what happens when the concentration of a reactant is increased in a system at equilibrium?

A The equilibrium shifts to the left. B The equilibrium shifts to the right. C The equilibrium constant changes. D The reaction stops completely.

20

What is the effect of adding more reactant to a system at equilibrium?

A Equilibrium shifts to the left B Equilibrium shifts to the right C Equilibrium does not change D The reaction stops

21

What is the system in a chemical reaction?

A The part of the universe being studied B Everything outside the reaction vessel C Only the solvent D Only the catalyst

22

Which of the following is NOT a factor affecting the rate of a reaction?

A Temperature B Concentration of reactants C Pressure D Volume of the container

23

What is activation energy?

A Energy released during reaction B Minimum energy required for a reaction to occur C Energy of products D Total energy of reactants

24

What does a double arrow (⇌) in a chemical equation show?

A The reaction is reversible. B The reaction is irreversible. C The reaction is very fast. D The reaction produces a gas.

25

In a calorimeter, heat change is measured by observing the change in:

A Mass of the reactant B Temperature of water C Volume of gas D Pressure of the system