chemistry MCQs - 9th class Chapter 05 Mcqs

1

What is the term for the total amount of thermal energy stored in a compound?

A

Activation Energy

B

Heat

C

Enthalpy

D

Kinetic Energy

2

In an exothermic reaction, the enthalpy change (ΔH) has a sign that is:

A

Positive

B

Negative

C

Neutral

D

Variable

3

Which process is endothermic?

A

Bond making

B

Combustion

C

Respiration

D

Bond breaking

4

What is the unit of measurement for enthalpy (H)?

A

Joule

B

kJ mol⁻¹

C

Calorie

D

Watt

5

Which of the following describes a chemical system?

A

Only the beaker

B

Only the reactants and products

C

The reactants, products, catalyst, and solvent

D

Everything outside the reaction vessel

6

When energy is transferred from the surroundings to the system, the change is called:

A

Exothermic

B

Isothermic

C

Endothermic

D

Adiabatic

7

The minimum energy that colliding particles must have for a successful collision is called:

A

Enthalpy

B

Kinetic Energy

C

Potential Energy

D

Activation Energy

8

What is the role of a catalyst in a reaction?

A

It increases the enthalpy of products

B

It increases the activation energy

C

It provides an alternative reaction pathway with lower activation energy

D

It undergoes permanent chemical change

9

The reaction 2H₂(g) + O₂(g) → 2H₂O(l) + 571.6 kJ is an example of:

A

An endothermic reaction

B

A reversible reaction

C

An exothermic reaction

D

A decomposition reaction

10

In an endothermic reaction, the energy of the products is _________ the energy of the reactants.

A

less than

B

equal to

C

more than

D

zero

11

What does ΔH represent in a chemical reaction?

A

The rate of reaction

B

The change in enthalpy

C

The activation energy

D

The total heat present

12

Which of the following is a primary role of lipids in the body?

A

To provide immediate energy

B

To act as a catalyst

C

To serve as a reserve energy store

D

To form structural components of muscles

13

Aerobic respiration occurs in the presence of which substance?

A

Nitrogen

B

Carbon Dioxide

C

Water

D

Oxygen

14

What are the products of the complete combustion of a fuel like natural gas?

A

Carbon and Hydrogen

B

Carbon monoxide and water

C

Carbon dioxide and water

D

Oxygen and heat

15

In the reaction N₂(g) + O₂(g) → 2NO(g) - 180.6 kJ, the reaction is:

A

Exothermic

B

Endothermic

C

Spontaneous

D

Catalyzed

16

The standard enthalpy of reaction (ΔH°) is measured under what temperature and pressure conditions?

A

25°C and 1 atm

B

100°C and 1 atm

C

0°C and 760 mm pressure

D

25 K and 760 mm pressure

17

When heat leaves a system, it results in a change of:

A

Activation energy

B

Reaction rate

C

Enthalpy

D

Pressure

18

Which term is used for a physical or chemical change under study?

A

Surrounding

B

Universe

C

System

D

Boundary

19

Fireworks are an example of what type of reaction?

A

Endothermic

B

Decomposition

C

Exothermic

D

Neutralization

20

The process of glycolysis splits one molecule of glucose into two molecules of:

A

Ethanol

B

Pyruvate

C

Lactic acid

D

ATP

21

What happens to the total enthalpy of a system when energy is absorbed during a reaction?

A

It decreases

B

It remains constant

C

It increases

D

It becomes zero

22

The formation of bonds between atoms is a process that is always:

A

Endothermic

B

Exothermic

C

Neutral

D

Slow

23

According to the text, Thomas Young was the first to use the word 'energy' in the field of:

A

Chemistry

B

Biology

C

Physics

D

Mathematics

24

In an energy profile diagram for an endothermic reaction, the sign of ΔH is:

A

Negative

B

Positive

C

Zero

D

ΔH is not shown

25

What is the main purpose of burning fuels like gas, oil, and coal?

A

To produce light

B

To produce chemical energy

C

To produce heat energy

D

To reduce air pollution

26

Anaerobic respiration occurs in the __________ of oxygen.

A

presence

B

absence

C

liquid form

D

gaseous form

27

The energy stored in a molecule in which atoms are bonded to each other is called:

A

Heat Energy

B

Kinetic Energy

C

Potential Energy

D

Chemical Energy

28

When a bond is broken, heat energy is:

A

Released

B

Absorbed

C

Destroyed

D

Created

29

What happens to the container during an exothermic reaction?

A

It gets cooler

B

It gets hotter

C

Its temperature does not change

D

It breaks

30

In the reaction C(s) + O₂(g) → CO₂(g) + 393.5 kJ, how much energy is evolved?

A

571.6 kJ

B

180.6 kJ

C

393.5 kJ

D

53.08 kJ

31

What is glycogen?

A

A type of lipid

B

A catalyst

C

The primary storage form of glucose

D

A product of anaerobic respiration

32

The energy of the transition state is always _________ than that of reactants and products.

A

lower

B

equal to

C

higher

D

negative

33

Which of the following acts as a catalyst in the hydrogenation of oil?

A

Platinum

B

Chlorine

C

Iron

D

Nickel

34

In the equation 2H₂(g) + O₂(g) → 2H₂O(g), the breaking of H-H and O=O bonds is:

A

An exothermic process

B

An endothermic process

C

A neutral process

D

A spontaneous process

35

The difference between the energy of reactants and the energy of products is called:

A

Activation energy

B

Kinetic energy

C

Bond energy

D

Enthalpy change of the reaction

36

What happens to weaker bonds during most chemical reactions?

A

They are formed in products

B

They remain unchanged

C

They are broken in reactants

D

They absorb less energy

37

Which part of 'Thermodynamics' is studied in chemical energetics?

A

The flow of energy in a chemical reaction

B

The speed of a reaction

C

The state of matter

D

The properties of the nucleus

38

During metabolism, chemical energy from food is converted into:

A

Light energy

B

Electrical energy

C

Heat energy

D

Potential energy

39

Excess food in the human body is stored as lipids in what type of cells?

A

Muscle cells

B

Liver cells

C

Nerve cells

D

Adipose cells

40

In the hypothetical reaction A₂ + B₂ → 2AB, what does the peak of the energy profile diagram represent?

A

Reactants

B

Products

C

Transition state

D

Activation energy

41

What are the products of anaerobic respiration in organisms like yeast?

A

ATP and Water

B

Ethanol and CO₂

C

Pyruvate and Oxygen

D

Glucose and Water

42

Which of these is NOT a form of energy mentioned in the introduction?

A

Chemical Energy

B

Heat Energy

C

Nuclear Energy

D

None of the above

43

Boiling water in a beaker is an example of an _________ process.

A

exothermic

B

endothermic

C

isobaric

D

isochoric

44

When NaOH and HCl are mixed, the temperature increases. The reaction is:

A

endothermic with a positive enthalpy change

B

endothermic with a negative enthalpy change

C

exothermic with a positive enthalpy change

D

exothermic with a negative enthalpy change

45

The bond dissociation energy of H₂ is given as:

A

498 kJ/mol

B

484 kJ/mol

C

435 kJ/mol

D

568 kJ/mol

46

If a reaction is exothermic, what is the nature of the reverse reaction?

A

Also exothermic

B

Endothermic

C

No reaction

D

Spontaneous

47

What substance is used to rotate turbines in power stations to generate electricity?

A

Hot air

B

High pressure steam

C

Natural gas

D

Molten coal

48

The formation of which hydrogen halide from its elements is an endothermic reaction?

A

HCl

B

HBr

C

HF

D

HI

49

Platinum acts as a catalyst in the production of:

A

Banaspati ghee

B

Ozone

C

H₂SO₄

D

Ammonia

50

In the energy profile diagram, what does Ea represent?

A

Enthalpy of reaction

B

Energy of products

C

Energy of reactants

D

Activation energy