chemistry MCQs - 11th class Chapter 11 Mcqs

1

The study of reaction rates and the factors that affect them is called:

A

Thermodynamics

B

Reaction Kinetics

C

Chemical Equilibrium

D

Stoichiometry

2

Which of the following reactions is typically the fastest?

A

Rusting of iron

B

Fermentation of sugars

C

Precipitation of AgCl

D

Weathering of stone

3

The slowest step in a multi-step reaction is known as the:

A

Activation step

B

Final step

C

First step

D

Rate determining step

4

The rate of a reaction is defined as the change in concentration of a reactant or product divided by the:

A

Temperature

B

Pressure

C

Time taken

D

Volume

5

The standard units for the rate of a reaction are:

A

mol dm³ s⁻¹

B

mol⁻¹ dm³ s⁻¹

C

mol dm⁻³ s

D

s⁻¹

6

The rate of reaction at a specific moment in time is called the:

A

Average rate

B

Overall rate

C

Instantaneous rate

D

Specific rate

7

In the rate equation Rate = k[A]ª[B]ᵇ, what does 'k' represent?

A

Order of reaction

B

Rate constant

C

Concentration of A

D

Temperature

8

The overall order of a reaction with the rate equation Rate = k[A]²[B]¹ is:

A

2

B

1

C

3

D

0

9

The order of a reaction is determined by:

A

Looking at the balanced chemical equation

B

Theoretical calculations

C

Experiment

D

The number of products

10

Reactions that are independent of the concentration of reactants are called:

A

First order

B

Second order

C

Fractional order

D

Zero order

11

The time required to convert 50% of reactants into products is called the:

A

Reaction time

B

Full-life period

C

Half-life period

D

Activation period

12

For a first-order reaction, the half-life period is:

A

Dependent on initial concentration

B

Inversely proportional to initial concentration

C

Directly proportional to initial concentration

D

Independent of initial concentration

13

For a second-order reaction, the half-life period is:

A

Independent of initial concentration

B

Inversely proportional to the initial concentration

C

Directly proportional to the initial concentration

D

Inversely proportional to the square of initial concentration

14

In the reaction NO₂(g) + CO(g) -> NO(g) + CO₂(g), the rate determining step involves:

A

One molecule of NO₂

B

One molecule of CO

C

Two molecules of NO₂

D

A molecule of NO₃ and CO

15

A species that has a temporary existence during a reaction mechanism is called a:

A

Catalyst

B

Reactant

C

Product

D

Reaction intermediate

16

The minimum amount of energy required for an effective collision is called:

A

Kinetic energy

B

Potential energy

C

Activation energy

D

Enthalpy of reaction

17

The unstable, high-energy combination of atoms formed during a reaction is the:

A

Reactant state

B

Product state

C

Transition state

D

Activated complex

18

In an exothermic reaction, the potential energy of the products is:

A

Higher than reactants

B

Equal to reactants

C

Lower than reactants

D

Zero

19

For an endothermic reaction, the sign of ΔH is:

A

Positive

B

Negative

C

Zero

D

Variable

20

According to the Arrhenius equation, the rate constant 'k' increases with:

A

Increasing activation energy

B

Decreasing temperature

C

Increasing temperature

D

Increasing pressure

21

A substance that alters the rate of a reaction but remains chemically unchanged is a:

A

Reactant

B

Product

C

Inhibitor

D

Catalyst

22

When a catalyst and reactants are in the same phase, the process is called:

A

Heterogeneous catalysis

B

Homogeneous catalysis

C

Autocatalysis

D

Enzyme catalysis

23

The hydrogenation of vegetable oils using finely divided Nickel is an example of:

A

Homogeneous catalysis

B

Autocatalysis

C

Enzyme catalysis

D

Heterogeneous catalysis

24

A catalyst helps to establish equilibrium:

A

Slower

B

Earlier

C

It does not affect equilibrium

D

It prevents equilibrium

25

A substance which promotes the activity of a catalyst is called a:

A

Poison

B

Inhibitor

C

Promoter

D

Substrate

26

A substance that retards the rate of a reaction is known as an:

A

Activator

B

Inhibitor

C

Catalyst

D

Promoter

27

When a product of a reaction acts as a catalyst for that same reaction, it is called:

A

Negative catalysis

B

Heterogeneous catalysis

C

Autocatalysis

D

Homogeneous catalysis

28

Complex protein molecules that catalyze organic reactions in living cells are called:

A

Inhibitors

B

Enzymes

C

Promoters

D

Hormones

29

The 'lock and key' model is used to describe the mechanism of:

A

Heterogeneous catalysis

B

Homogeneous catalysis

C

Enzyme catalysis

D

Autocatalysis

30

The rate of an enzyme-catalyzed reaction is maximum at its:

A

Lowest temperature

B

Highest pressure

C

Optimum pH

D

Initial concentration

31

Generally, for every 10K rise in temperature, the reaction rate:

A

Is halved

B

Is quadrupled

C

Remains unchanged

D

Doubles

32

Which physical method is applicable for determining reaction rate if a reactant absorbs UV radiation?

A

Dilatometric method

B

Refractrometric method

C

Spectrometry

D

Electrical conductivity

33

Which method for determining reaction rate is suitable for reactions involving ions?

A

Optical rotation method

B

Spectrometry

C

Dilatometric method

D

Electrical conductivity method

34

The hydrolysis of an ester in the presence of an acid is an example of a:

A

Zero order reaction

B

Second order reaction

C

Pseudo first order reaction

D

Third order reaction

35

For the reaction 2FeCl₃ + 6KI -> products, the experimentally determined order is:

A

First order

B

Second order

C

Eighth order

D

Third order

36

In the Arrhenius plot, a graph is plotted between log k and:

A

T

B

1/T

C

Ea

D

R

37

The slope of the Arrhenius plot is equal to:

A

-Ea / 2.303R

B

Ea / R

C

-R / 2.303Ea

D

k / A

38

Increasing the surface area of solid reactants generally leads to:

A

A decrease in reaction rate

B

No change in reaction rate

C

An increase in reaction rate

D

A change in reaction order

39

Light can increase the rate of which type of reactions?

A

Neutralization

B

Precipitation

C

Photochemical reactions

D

Combustion

40

The reaction between H₂ and Cl₂ is explosive in:

A

Darkness

B

Daylight

C

Sunlight

D

Red light

41

The specific rate constant 'k' of a reaction is equal to the rate of reaction when concentrations of reactants are:

A

Zero

B

Unity

C

Double

D

Half

42

The half-life of radioactive decay is always:

A

Zero order

B

First order

C

Second order

D

Fractional order

43

What is the order of the reaction CHCl₃ + Cl₂ -> CCl₄ + HCl, if its rate equation is Rate = k[CHCl₃][Cl₂]¹/²?

A

1

B

2

C

1.5

D

2.5

44

In the Haber's process for ammonia synthesis, iron is used as a:

A

Promoter

B

Inhibitor

C

Reactant

D

Catalyst

45

Traces of arsenic can make which catalyst ineffective in the contact process?

A

Iron

B

Platinum

C

Nickel

D

Manganese dioxide

46

What is the conjugate base of the acid in a reaction?

A

A negatively charged ion or a neutral species produced by the release of a proton

B

A positively charged ion produced by the acceptance of a proton

C

The substance which alters the rate of reaction

D

A species with temporary existence

47

What is the purpose of chilling the reaction mixture sample during the titration method for ester hydrolysis?

A

To speed up the reaction

B

To stop the reaction

C

To dissolve the indicator

D

To increase concentration

48

For effective collisions, molecules must possess activation energy and:

A

High kinetic energy

B

Be in the same phase

C

Proper orientation

D

Low potential energy

49

Which of these is NOT a characteristic of a catalyst?

A

It remains unchanged in mass at the end

B

It is specific in its action

C

It starts a reaction that is not thermodynamically feasible

D

It helps equilibrium to be established earlier