Chemical Changes: Interactive Quizzes and Learning Materials

Question 1

What is a defining characteristic of a chemical change?

Accepted Answer

A change in the substance's composition

Answer

A change in the substance's appearance

Answer

A change in the substance's temperature

Answer

A change in the substance's volume

Question 2

Chemical reactions involve changes in the chemical composition and structure of substances. Which of the following is NOT a type of chemical reaction?

Accepted Answer

Political reaction

Answer

Neutralization reaction

Answer

Combustion reaction

Answer

Precipitation reaction

Question 3

When a chemical change takes place, new substances are created. Which of these processes is an example of a chemical change?

Accepted Answer

Burning magnesium

Answer

Boiling water

Answer

Dissolving sugar in water

Answer

Melting ice

Question 4

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

Accepted Answer

Reversibility

Answer

Formation of a new substance

Answer

Energy changes

Question 5

What distinguishes chemical changes from physical changes?

Accepted Answer

Creation of a new substance

Answer

Energy release or absorption

Answer

Alteration in physical state

Question 6

A chemical change is a change in which a new substance is formed. Which of the following is an example of a chemical change?

Accepted Answer

Burning wood

Answer

Melting ice

Answer

Dissolving salt in water

Answer

Crushing a can

Question 7

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

Accepted Answer

Change in physical state

Answer

Formation of a new substance

Answer

Release or absorption of energy

Question 8

Chemical changes involve the rearrangement of atoms to form new substances. Which of the following is NOT a characteristic of a chemical change?

Accepted Answer

Change in temperature

Answer

Formation of a new substance

Answer

Change in color or appearance

Answer

Release or absorption of energy

Question 9

When a substance undergoes combustion in the presence of oxygen, which product is primarily released?

Accepted Answer

Carbon dioxide

Answer

Oxygen

Answer

Water

Answer

Nitrogen

Question 10

In a reduction reaction, what happens to the oxidation number of the element being reduced?

Accepted Answer

Decreases

Answer

Increases

Question 11

In a redox reaction, oxidation refers to:

Accepted Answer

Losing electrons

Answer

Gaining electrons

Answer

Gaining oxygen

Answer

Losing hydrogen

Question 12

Which property is characteristic of a physical change but not a chemical change?

Accepted Answer

Substance remains unchanged

Answer

Change is irreversible

Answer

Gas is produced

Answer

Energy is released or absorbed

Question 13

On the pH scale, which value indicates a neutral solution?

Accepted Answer

7

Answer

1

Answer

14

Question 14

When iron is exposed to air and moisture, it undergoes a chemical change called rusting. Which of the following processes accurately describes this transformation?

Accepted Answer

A redox reaction where iron loses electrons to oxygen, resulting in the formation of iron oxide (rust).

Answer

A physical change where iron's appearance changes but its composition remains the same.

Answer

An endothermic reaction where iron absorbs energy from its surroundings.

Answer

A combustion reaction where iron burns in the presence of oxygen, releasing heat and light.

Question 15

In a decomposition reaction, what is the defining characteristic of the change that occurs to the reactant?

Accepted Answer

The reactant breaks down into two or more simpler substances.

Answer

The reactant changes its color or appearance.

Answer

The reactant releases energy in the form of heat or light.

Question 16

In a redox reaction, what is the term for when a substance loses electrons?

Accepted Answer

Oxidation

Answer

Reduction

Answer

Electron transfer

Answer

Neutralization

Question 17

What type of chemical reaction occurs when a substance combines with oxygen to form a new compound?

Accepted Answer

Oxidation

Answer

Neutralization

Answer

Decomposition

Question 18

Decomposition reactions involve the breakdown of a complex substance into simpler products. Which of the following reactions is an example of decomposition?

Accepted Answer

Breaking down of hydrogen peroxide into water and oxygen

Answer

Rusting of iron

Answer

Burning of wood

Question 19

During a redox reaction, when an element is reduced, what happens to its oxidation number?

Accepted Answer

Decreases

Answer

Increases

Answer

Stays the same

Question 20

What is a defining characteristic of a chemical change?

Accepted Answer

Creation of new substances

Answer

Color alteration

Answer

Temperature change

Question 21

What is the key difference between a chemical change and a physical change?

Accepted Answer

Formation of new substances

Answer

Change in appearance

Answer

Change in color

Answer

Release or absorption of energy

Question 22

An endothermic reaction is characterized by:

Accepted Answer

Absorbing heat from the surroundings, leading to a decrease in temperature

Answer

Releasing heat into the surroundings, causing an increase in temperature

Answer

Having no effect on the temperature of the surroundings

Answer

Producing light energy

Question 23

Which of these is **not** a chemical change?

Accepted Answer

Ice melting

Answer

Wood burning

Answer

Iron rusting

Question 24

Predict the products of the chemical reaction between magnesium (Mg) and hydrochloric acid (HCl). Explain your prediction based on the chemical bonding and reactivity of the reactants.

Accepted Answer

Magnesium chloride (MgCl₂) and hydrogen gas (H₂)

Answer

Magnesium oxide (MgO) and chlorine gas (Cl₂)

Answer

Hydrogen chloride (HCl) and magnesium hydroxide (Mg(OH)₂)

Answer

No reaction occurs.

Question 25

In a science experiment involving chemical reactions, which safety measures are crucial to follow? Choose all that apply.

Accepted Answer

Wear proper protective gear (e.g., gloves, eye protection).

Accepted Answer

Work in a well-ventilated area or fume cupboard.

Accepted Answer

Adjust the Bunsen burner's air hole for complete combustion.

Answer

Disregard safety instructions to save time.

Question 26

When an acid reacts with a base, the resulting solution is typically:

Accepted Answer

Neutral

Answer

Acidic

Answer

Basic

Answer

Unstable

Question 27

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

Accepted Answer

Rusting of iron

Answer

Burning of methane

Answer

Dissolving of salt in water

Answer

Condensation of water vapor

Question 28

What is the primary function 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

Question 29

Which of the following is considered a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Citric acid

Question 30

What is the oxidation number of nitrogen in nitric acid (HNO3)?

Accepted Answer

+5

Answer

-3

Answer

-1

Answer

+3

Question 31

Which of the following is **not** a type of chemical change?

Accepted Answer

Physical change

Answer

Acid-base reaction

Answer

Redox reaction

Answer

Combustion

Question 32

State the **law of conservation of mass**.

Accepted Answer

Mass cannot be created or destroyed in a chemical reaction.

Answer

Mass can be created or destroyed in a chemical reaction.

Answer

Mass is always conserved in a physical change.

Answer

Mass is only conserved in a chemical change.

Question 33

What is the pH of a neutral solution?

Accepted Answer

7

Answer

0

Answer

14

Answer

It depends on the temperature

Question 34

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.

Question 35

What type of reaction occurs when an acid and a base interact?

Accepted Answer

Neutralization reaction

Answer

Oxidation-reduction reaction

Answer

Decomposition reaction

Answer

Combustion reaction

Question 36

What is the pH value of a neutral solution?

Accepted Answer

7

Answer

0

Answer

14

Answer

10

Question 37

Which of the following acts as an oxidizing agent?

Accepted Answer

Oxygen

Answer

Sodium

Answer

Hydrogen

Answer

Carbon

Question 38

What is the name of a substance that accelerates a chemical reaction without being consumed?

Accepted Answer

Catalyst

Answer

Inhibitor

Answer

Reactant

Answer

Product

Question 39

Which of the following is NOT a type of chemical bond?

Accepted Answer

Gravitational bond

Answer

Ionic bond

Answer

Covalent bond

Answer

Metallic bond

Question 40

What is the term for a substance that donates hydrogen ions in water?

Accepted Answer

Acid

Answer

Base

Answer

Salt

Answer

Alkali

Question 41

In a redox reaction, which species undergoes reduction?

Accepted Answer

The species that gains electrons

Answer

The species that loses electrons

Answer

The species that undergoes a change in oxidation state

Answer

The species that remains unchanged

Question 42

What is the name of the law that states that mass is neither created nor destroyed in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Answer

Law of Multiple Proportions

Answer

Law of Definite Proportions

Answer

Law of Combining Volumes

Question 43

Which of the following substances is a strong electrolyte?

Accepted Answer

Sodium chloride

Answer

Glucose

Answer

Water

Answer

Ethanol

Question 44

What is the pH value of a neutral solution?

Accepted Answer

7

Answer

0

Answer

14

Answer

10

Question 45

What gas is produced when an acid reacts with a carbonate?

Accepted Answer

Carbon dioxide

Answer

Hydrogen

Answer

Oxygen

Answer

Nitrogen

Question 46

Which of the following is a balanced chemical equation?

Accepted Answer

C6H12O6 + 6O2 → 6CO2 + 6H2O

Answer

2H2 + O → H2O

Answer

CH4 + 2O2 → CO2 + H2O

Answer

Fe + HCl → FeCl2 + H

Question 47

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

Accepted Answer

Strength of a magnetic field

Answer

Concentration of reactants

Answer

Temperature

Answer

Presence of a catalyst

Question 48

The Law of Conservation of Mass states that:

Accepted Answer

Mass is neither created nor destroyed in any chemical reaction.

Answer

Energy is neither created nor destroyed in any chemical reaction.

Answer

The number of atoms of each element remains unchanged in any chemical reaction.

Answer

The volume of gases involved in any chemical reaction remains constant.

Question 49

Which of the following is considered a strong acid?

Accepted Answer

Hydrochloric acid

Answer

Acetic acid

Answer

Carbonic acid

Answer

Ammonia

Question 50

The pH scale primarily measures:

Accepted Answer

The acidity or alkalinity of a solution

Answer

The concentration of hydroxide ions in a solution

Answer

The temperature of a solution

Answer

The electrical conductivity of a solution

Question 51

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

Accepted Answer

Burning of wood

Answer

Dissolving sugar in water

Answer

Reaction of an acid with a base

Answer

Melting of ice

Question 52

Define sublimation, the process by which a solid directly transforms into a gas.

Accepted Answer

Sublimation: solid to gas

Answer

Evaporation: liquid to gas

Answer

Condensation: gas to liquid

Answer

Deposition: gas to solid

Question 53

Determine the empirical formula of a compound containing 12 g of carbon, 2 g of hydrogen, and 32 g of oxygen.

Accepted Answer

CH2O

Answer

CH3O

Answer

CH4O2

Answer

C2H2O4

Question 54

Explain the role of a catalyst in a chemical reaction.

Accepted Answer

Decrease activation energy

Answer

Increase activation energy

Answer

Alter reaction products

Answer

Prevent reaction from occurring

Question 55

Which substance qualifies as a strong electrolyte?

Accepted Answer

Sodium chloride

Answer

Sugar

Answer

Carbon dioxide

Answer

Water

Question 56

What is the term for a chemical reaction that releases heat energy into its surroundings?

Accepted Answer

Exothermic

Answer

Endothermic

Answer

Thermochemical

Answer

Combustion

Question 57

Which of the following factors does NOT influence the rate of a chemical reaction?

Accepted Answer

Shape of the reaction vessel

Answer

Concentration of reactants

Answer

Temperature

Answer

Nature of the catalyst

Question 58

Determine the molar ratio of sodium to chlorine in sodium chloride (NaCl).

Accepted Answer

1:1

Answer

1:2

Answer

2:1

Answer

1:3

Question 59

Identify the strong acid from the following options.

Accepted Answer

Hydrochloric acid (HCl)

Answer

Acetic acid (CH3COOH)

Answer

Carbonic acid (H2CO3)

Answer

Ammonia (NH3)

Question 60

What is the conjugate base of a weak acid?

Accepted Answer

A weak base

Answer

A strong base

Answer

A neutral compound

Answer

An acidic compound

Question 61

Which of the following acts as a reducing agent in a chemical reaction?

Accepted Answer

Hydrogen gas (H2)

Answer

Oxygen gas (O2)

Answer

Sodium chloride (NaCl)

Answer

Potassium permanganate (KMnO4)

Question 62

Which of the following processes is a redox reaction?

Accepted Answer

Combustion of methane

Answer

Neutralization of an acid and a base

Answer

Dissolving a salt in water

Answer

Displacement of a metal from a salt solution

Question 63

Which factor does not affect the rate of a chemical reaction?

Accepted Answer

Nature of the product

Answer

Concentration of reactants

Answer

Temperature

Answer

Surface area of reactants

Question 64

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

Accepted Answer

44 g/mol

Answer

28 g/mol

Answer

56 g/mol

Answer

60 g/mol