Chemical Reactions: Interactive Quizzes for Year 7 Science

Question 1

When a chemical reaction releases energy, what type of reaction is it?

Accepted Answer

Exothermic

Answer

Endothermic

Answer

Neutralization

Question 2

Which of the following reactions releases energy?

Accepted Answer

Burning of fuel

Answer

Dissolving salt in water

Answer

Freezing of water

Answer

Melting of ice

Question 3

What is the correct chemical equation for the reaction between hydrogen and oxygen?

Accepted Answer

2H + O2 -> 2H2O

Answer

H + O -> H2O

Answer

H + 2O -> H2O2

Answer

2H + O -> 2H2O

Question 4

What is the product of the reaction between sodium hydroxide and hydrochloric acid?

Accepted Answer

Sodium chloride and water

Answer

Sodium hydroxide and hydrogen chloride

Answer

Hydrochloric acid and water

Answer

Sodium chloride and hydrogen gas

Question 5

What is the pH of a solution with a hydrogen ion concentration of 1 x 10^-7 M?

Accepted Answer

7

Answer

0

Answer

10

Answer

14

Question 6

What do catalysts do in chemical reactions?

Accepted Answer

Decrease the activation energy of the reaction

Answer

Increase the activation energy of the reaction

Answer

Change the products of the reaction

Answer

Stop the reaction from occurring

Question 7

Combustion is a specific type of chemical reaction called a(n):

Accepted Answer

Combustion reaction

Answer

Decomposition reaction

Answer

Synthesis reaction

Question 8

Which of the following processes releases energy?

Accepted Answer

Burning wood

Answer

Melting ice

Answer

Dissolving sugar in water

Question 9

What is the chemical formula for carbon dioxide?

Accepted Answer

CO2

Answer

CO

Answer

CO3

Question 10

What is the product of the reaction between calcium and chlorine?

Accepted Answer

Calcium chloride

Answer

Calcium oxide

Answer

Calcium hydroxide

Question 11

Which of the following is a balanced chemical equation?

Accepted Answer

2H2 + O2 → 2H2O

Answer

2H + O → H2O

Answer

H2 + O2 → H2O

Question 12

Rust is formed when iron reacts with:

Accepted Answer

Oxygen

Answer

Water

Answer

Carbon dioxide

Question 13

In the reaction: 2H2 + O2 → 2H2O, which type of reaction is taking place?

Accepted Answer

Combination

Answer

Decomposition

Answer

Single displacement

Answer

Double displacement

Question 14

Which reaction releases heat?

Accepted Answer

Burning a candle

Answer

Melting ice

Answer

Photosynthesis

Answer

Dissolving salt in water

Question 15

What speeds up a chemical reaction?

Accepted Answer

A catalyst

Answer

Slowing down the reaction

Answer

Changing the products

Answer

Preventing the reaction

Question 16

Which of these is a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Vinegar

Answer

Lemon juice

Answer

Sodium bicarbonate

Question 17

What is the pH of a neutral solution?

Accepted Answer

7

Answer

Less than 7

Answer

Greater than 7

Answer

0

Question 18

Which gas traps heat in the Earth's atmosphere?

Accepted Answer

Carbon dioxide

Answer

Nitrogen

Answer

Oxygen

Answer

Hydrogen

Question 19

What is the chemical symbol for sodium?

Accepted Answer

Na

Answer

S

Answer

N

Answer

So

Question 20

Which of the following is NOT considered a type of chemical reaction?

Accepted Answer

Evaporation

Answer

Decomposition

Answer

Combination

Answer

Neutralization

Question 21

What happens to the energy when a fuel burns?

Accepted Answer

Energy is released

Answer

Energy is absorbed

Answer

No energy change occurs

Answer

Energy is stored

Question 22

Which of the following is a property of exothermic reactions?

Accepted Answer

Release of heat

Answer

Absorption of heat

Answer

Decrease in temperature

Answer

No temperature change

Question 23

Which of these is an example of a chemical change?

Accepted Answer

Burning of paper

Answer

Melting of ice

Answer

Dissolving sugar in water

Answer

Boiling of water

Question 24

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

Accepted Answer

To decrease the activation energy of the reaction

Answer

To increase the activation energy of the reaction

Answer

To provide reactants with energy

Answer

To alter the products of the reaction

Question 25

Which of the following is an example of a redox reaction?

Accepted Answer

Rusting of iron

Answer

Neutralization of an acid and a base

Answer

Dissolution of salt in water

Answer

Formation of ice crystals

Question 26

According to the Law of Conservation of Mass, what happens to the total mass of the reactants and products in a chemical reaction?

Accepted Answer

It stays the same.

Answer

It increases.

Answer

It decreases.

Answer

It depends on the type of reaction.

Question 27

What happens to the energy of the reactants in an exothermic reaction?

Accepted Answer

It is released into the surroundings

Answer

It is absorbed from the surroundings

Answer

It remains the same

Question 28

What is the name of the gas produced when an acid and a metal react?

Accepted Answer

Hydrogen

Answer

Oxygen

Answer

Carbon dioxide

Question 29

Which of these is a chemical change?

Accepted Answer

Burning of paper

Answer

Melting of ice

Answer

Boiling of water

Question 30

What is the product of the reaction between sodium and chlorine?

Accepted Answer

Sodium chloride

Answer

Sodium hydroxide

Question 31

Which of these is a catalyst?

Accepted Answer

A substance that speeds up a reaction without being consumed

Answer

A substance that slows down a reaction

Answer

A substance that changes the color of a reaction

Question 32

What is the name of the process by which plants use sunlight to make their own food?

Accepted Answer

Photosynthesis

Answer

Respiration

Answer

Combustion

Question 33

What is the name of the law that states that mass cannot be created or destroyed in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Answer

Law of Definite Proportions

Answer

Law of Multiple Proportions

Question 34

Which process releases heat and light?

Accepted Answer

Burning a candle

Answer

Freezing water

Answer

Boiling water

Answer

Melting ice

Question 35

What happens in a combination reaction?

Accepted Answer

Two or more elements come together to form a compound.

Answer

A compound breaks down into simpler substances.

Answer

One element replaces another element in a compound.

Answer

Two compounds exchange ions to form new compounds.

Question 36

What does a catalyst do in a chemical reaction?

Accepted Answer

It speeds up the reaction without being used up.

Answer

It slows down the reaction.

Answer

It changes the type of reaction that occurs.

Answer

It has no effect on the reaction.

Question 37

What is the difference between an exothermic and an endothermic reaction?

Accepted Answer

Exothermic reactions release energy, while endothermic reactions absorb energy.

Answer

Endothermic reactions release energy, while exothermic reactions absorb energy.

Answer

Exothermic reactions occur at lower temperatures than endothermic reactions.

Answer

Endothermic reactions occur at higher temperatures than exothermic reactions.

Question 38

What is the balanced equation for the reaction between sodium and chlorine?

Accepted Answer

2Na + Cl2 → 2NaCl

Answer

Na + Cl2 → NaCl

Answer

Na2 + Cl2 → 2NaCl

Answer

2Na + 2Cl2 → 4NaCl

Question 39

What is the molar mass of carbon dioxide (CO2)?

Accepted Answer

44 g/mol

Answer

12 g/mol

Answer

24 g/mol

Answer

32 g/mol

Question 40

What happens to the energy of a system when an exothermic reaction occurs?

Accepted Answer

Energy is released

Answer

Energy is absorbed

Answer

Energy remains the same

Answer

Energy converted into matter

Question 41

What is the purpose of a catalyst in a chemical reaction?

Accepted Answer

To speed up the reaction

Answer

To slow down the reaction

Answer

To change the type of reaction

Answer

To absorb energy from the reaction

Question 42

Which of the following is a characteristic of an endothermic reaction?

Accepted Answer

Energy is absorbed

Answer

Energy is released

Answer

Temperature decreases

Answer

Temperature increases

Question 43

What is the balanced chemical equation for the reaction between hydrogen and oxygen to form water?

Accepted Answer

2H + 2O → 2H₂O

Answer

H + O → H₂O

Answer

2H + O → H₂O

Answer

H + 2O → H₂O

Question 44

What is the name of the process by which a metal combines with oxygen to form an oxide?

Accepted Answer

Oxidation

Answer

Reduction

Answer

Corrosion

Answer

Neutralisation

Question 45

Which of the following is not considered a chemical reaction type?

Accepted Answer

Evaporation

Answer

Synthesis

Answer

Decomposition

Answer

Neutralization

Question 46

When a substance burns, what form of energy is released?

Accepted Answer

Heat

Answer

Light

Answer

Sound

Answer

Electricity

Question 47

What is the difference between an exothermic and an endothermic reaction?

Accepted Answer

Exothermic reactions release energy, while endothermic reactions absorb energy.

Answer

Endothermic reactions release energy, while exothermic reactions absorb energy.

Answer

Exothermic reactions involve bond breaking, while endothermic reactions involve bond formation.

Answer

Endothermic reactions involve bond breaking, while exothermic reactions involve bond formation.

Question 48

Which of the following is an example of a physical change?

Accepted Answer

Melting of ice

Answer

Rusting of iron

Answer

Burning of wood

Answer

Electrolysis of water

Question 49

In the reaction between hydrogen and oxygen, what acts as the catalyst?

Accepted Answer

Platinum

Answer

Carbon dioxide

Answer

Water

Answer

Nitrogen

Question 50

Which of the following is classified as a weak acid?

Accepted Answer

Acetic acid

Answer

Hydrochloric acid

Answer

Sulfuric acid

Answer

Nitric acid

Question 51

What is the pH of a neutral solution?

Accepted Answer

7

Answer

0

Answer

14

Answer

-7

Question 52

Which of the following is a hydrocarbon?

Accepted Answer

Methane

Answer

Ethanol

Answer

Ammonia

Answer

Sodium chloride

Question 53

What is the primary component of air?

Accepted Answer

Nitrogen

Answer

Oxygen

Answer

Carbon dioxide

Answer

Helium

Question 54

Which of the following is a characteristic of a physical change?

Accepted Answer

The substance changes form

Answer

The substance changes composition

Answer

A new substance is formed

Answer

Energy is released or absorbed

Question 55

What type of reaction occurs when sodium hydroxide (NaOH) reacts with hydrochloric acid (HCl)?

Accepted Answer

Neutralization

Answer

Combustion

Answer

Oxidation

Answer

Decomposition

Question 56

Which of the following is a product of the reaction between methane (CH4) and oxygen (O2)?

Accepted Answer

Carbon dioxide

Answer

Water

Answer

Sodium chloride

Answer

Iron oxide

Question 57

What is the energy change associated with an endothermic reaction?

Accepted Answer

Energy is absorbed

Answer

Energy is released

Answer

No energy change occurs

Answer

Energy is converted into light

Question 58

Which of the following factors does not affect the rate of a chemical reaction?

Accepted Answer

Color of the reactants

Answer

Temperature

Answer

Concentration of reactants

Answer

Surface area of reactants

Question 59

What is the empirical formula of a compound containing 80% carbon and 20% hydrogen, and no other elements?

Accepted Answer

CH

Answer

CH2

Answer

CH3

Answer

CH4

Question 60

Which of the following is a weak base?

Accepted Answer

Ammonium hydroxide

Answer

Sodium hydroxide

Answer

Potassium hydroxide

Answer

Calcium hydroxide

Question 61

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

Accepted Answer

To decrease the activation energy of the reaction

Answer

To increase the activation energy of the reaction

Answer

To change the products of the reaction

Answer

To prevent the reaction from occurring