Chemical Changes: Interactive Quizzes and Learning Materials

Question 1

Which of the following is NOT a common observation during a chemical reaction?

Accepted Answer

Change in shape

Answer

Color change

Answer

Temperature change

Answer

Gas production

Question 2

When a chemical reaction happens, what can be a sign that it has taken place?

Accepted Answer

A new substance is made.

Accepted Answer

The temperature of the mixture goes up.

Accepted Answer

Bubbles form in the mixture.

Answer

The color of the mixture stays the same.

Question 3

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

Accepted Answer

Chemical changes create new substances, while physical changes do not.

Answer

Physical changes can be reversed, while chemical changes cannot.

Answer

Physical changes involve the movement of atoms, while chemical changes do not.

Answer

Physical changes are always hot, while chemical changes are always cold.

Question 4

Which of the following is NOT a sign that a chemical reaction has occurred?

Accepted Answer

No visible change

Answer

A change in temperature

Answer

The formation of a gas

Answer

A change in color

Question 5

When a chemical change happens, what might you notice?

Accepted Answer

A change in color, like when iron rusts

Accepted Answer

A release of heat, like when you burn wood

Accepted Answer

A smell, like when vinegar and baking soda mix

Answer

A change in shape, like when water freezes

Question 6

When a chemical reaction takes place, there are often noticeable changes that happen. Which of these is NOT a sign that a chemical reaction has taken place?

Accepted Answer

The formation of a puddle of water

Answer

A change in color

Answer

The formation of a gas

Answer

A change in temperature

Question 7

Which of the following is a clear sign that a chemical reaction has taken place?

Accepted Answer

A change in color

Accepted Answer

A change in temperature

Accepted Answer

Formation of bubbles or gases

Answer

No visible changes

Question 8

What is a sign that a chemical reaction has happened?

Accepted Answer

A change in color

Accepted Answer

A change in temperature

Answer

A change in shape

Answer

A change in size

Question 9

Which of these is NOT a sign that a chemical reaction has occurred?

Accepted Answer

No change in appearance

Answer

A change in color

Answer

Bubbles forming

Answer

A change in temperature

Question 10

Which of the following is NOT a sign that a chemical reaction has happened?

Accepted Answer

A change in the boiling point of a substance

Answer

A change in color

Answer

The release of a gas

Answer

The release or absorption of heat

Question 11

Which of these is NOT an indication of a chemical reaction occurring?

Accepted Answer

No change in appearance

Answer

A change in color

Answer

The formation of a gas

Answer

A change in temperature

Question 12

During a chemical change, what happens to the substances involved?

Accepted Answer

They transform into entirely new substances.

Answer

They alter their color, but not their composition.

Answer

They change in size, becoming larger or smaller.

Answer

They change in weight, becoming lighter or heavier.

Question 13

Which of these is **not** always a sign that a chemical reaction has happened?

Accepted Answer

Change in size

Answer

Change in color

Answer

Change in temperature

Answer

Formation of a gas

Question 14

Which property is characteristic of acids?

Accepted Answer

Reacts with metals to produce hydrogen gas

Answer

Slippery to the touch

Answer

Turns red litmus paper blue

Answer

Has a pH greater than 7

Question 15

Which of these actions results in a chemical change?

Accepted Answer

Burning a piece of paper

Answer

Melting ice

Answer

Dissolving salt in water

Question 16

In a chemical reaction, we focus on energy changes. Which topic explores these energy transformations?

Accepted Answer

Energy Differences between Reactants and Products

Answer

Signs of a Chemical Reaction

Answer

Types of Chemical Reactions

Question 17

What is the pH of a neutral substance?

Accepted Answer

7

Answer

0

Answer

14

Question 18

When red litmus paper is dipped into a basic solution, what color will it turn?

Accepted Answer

Blue

Answer

Red

Answer

Green

Answer

Yellow

Question 19

When a chemical change occurs, which of the following is a key characteristic that you would observe?

Accepted Answer

Atoms are rearranged to form new substances

Answer

The color of the substance changes

Answer

The substance becomes more or less soluble in water

Answer

The temperature of the substance increases

Question 20

What is a characteristic of acids?

Accepted Answer

They have a sour taste

Accepted Answer

They turn blue litmus paper red

Answer

They feel slippery

Question 21

Which of the following is NOT usually a sign that a chemical reaction has occurred?

Accepted Answer

No bubbles forming

Answer

Change in color

Answer

Change in smell

Answer

Change in temperature

Question 22

Antacids are used to relieve heartburn and indigestion caused by excess stomach acid. Which characteristic of antacids enables them to neutralize stomach acid?

Accepted Answer

Antacids react with stomach acid to form water and a salt.

Answer

Antacids have a pH lower than 7.

Question 23

Which of these is a chemical change?

Accepted Answer

Wood burning

Accepted Answer

Iron rusting

Answer

Ice melting

Answer

Sugar dissolving in water

Question 24

What indicates that a chemical change has taken place?

Accepted Answer

The formation of new substances

Answer

A change in the form of a substance, without a change in its chemical composition

Question 25

Why do tiny water droplets form on the outside of a glass containing a cold drink?

Accepted Answer

The cold drink cools the air, causing water vapor to condense.

Answer

The cold drink attracts water molecules from the air.

Answer

The drink absorbs heat from the air, causing the air to condense.

Answer

The drink evaporates and the water vapor recondenses on the glass.

Question 26

In a chemical reaction, what are the substances called that change?

Accepted Answer

Reactants

Answer

Products

Answer

Atoms

Question 27

What is a chemical change? Describe the process that occurs during a chemical change.

Accepted Answer

A change in the chemical composition of a substance, involving the rearrangement of atoms or molecules to form new substances.

Answer

A change in the physical appearance of a substance, such as a change in color or shape.

Question 28

Which of these is NOT a sign that a chemical reaction has occurred?

Accepted Answer

No change in appearance

Answer

A change in color

Answer

The production of heat

Answer

The formation of bubbles

Question 29

Which of the following is a sign that a chemical reaction has occurred?

Accepted Answer

Change in color

Accepted Answer

Change in temperature

Answer

Change in shape

Answer

Change in mass

Question 30

What are three signs that a chemical change is happening?

Accepted Answer

Change in color

Accepted Answer

Change in temperature

Accepted Answer

Formation of bubbles

Answer

Change in shape

Question 31

Which of the following is NOT an indication that a chemical reaction has taken place?

Accepted Answer

No change in appearance

Answer

A change in color

Answer

The release of a gas

Answer

A change in temperature

Question 32

When an acid and a base react, what is the name of the substance that is formed?

Accepted Answer

Salt

Answer

Acid

Answer

Base

Question 33

Which of these is NOT a sign that a chemical reaction has happened?

Accepted Answer

A change in the mass of the substances involved

Answer

A change in temperature

Answer

A change in color

Answer

The formation of a solid

Question 34

When iron rusts, which of the following changes does NOT occur?

Accepted Answer

An increase in temperature

Answer

A change in color from shiny to reddish-brown

Answer

The formation of a flaky substance

Question 35

Which everyday process involves an endothermic reaction?

Accepted Answer

Melting ice

Answer

Burning fuel in a car

Answer

Rusting of iron

Answer

Cooking food

Question 36

Catalysts are substances that play a crucial role in chemical reactions. How do catalysts work and what impact do they have on the reaction rate?

Accepted Answer

Catalysts provide an alternative path for a reaction to occur, reducing the activation energy and speeding up the reaction rate.

Answer

Catalysts slow down chemical reactions.

Answer

Catalysts are used up in chemical reactions.

Question 37

Chemical reactions can involve energy changes. Which of the following statements about energy in chemical reactions is correct?

Accepted Answer

Exothermic reactions release energy, while endothermic reactions absorb energy.

Answer

Energy is always absorbed during chemical reactions.

Answer

Energy is always released during chemical reactions.

Answer

Exothermic reactions absorb energy, while endothermic reactions release energy.

Question 38

How does our knowledge of chemical changes impact various fields?

Accepted Answer

It aids in the development of targeted medicines for specific diseases.

Accepted Answer

It enables the production of fertilizers, boosting crop yields.

Accepted Answer

It contributes to the development of more efficient energy sources.

Answer

It has no practical applications in daily life.

Question 39

Which of the following is not an element?

Accepted Answer

Water

Answer

Gold

Answer

Carbon

Answer

Oxygen

Question 40

What is the chemical symbol for sodium?

Accepted Answer

Na

Answer

So

Answer

Sd

Answer

Sm

Question 41

What is the process called when two or more substances combine to form a new substance?

Accepted Answer

Chemical reaction

Answer

Physical change

Answer

Decomposition

Answer

Combustion

Question 42

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

Accepted Answer

Burning wood

Answer

Melting ice

Answer

Crushing a can

Answer

Mixing salt and water

Question 43

What is the name of the table that organizes all the known elements?

Accepted Answer

Periodic table

Answer

Element table

Answer

Chemical table

Answer

Atomic table

Question 44

What is the atomic number of an element?

Accepted Answer

The number of protons in its nucleus

Answer

The number of electrons in its nucleus

Answer

The number of neutrons in its nucleus

Answer

The number of electrons in its outermost shell

Question 45

Which of the following is a noble gas?

Accepted Answer

Helium

Answer

Hydrogen

Answer

Nitrogen

Answer

Carbon

Question 46

What is the name of the force that holds atoms together to form molecules?

Accepted Answer

Covalent bond

Answer

Ionic bond

Answer

Metallic bond

Answer

Hydrogen bond

Question 47

Which of the following is a metal?

Accepted Answer

Iron

Answer

Oxygen

Answer

Nitrogen

Answer

Chlorine

Question 48

In a chemical reaction, what's the difference between reactants that run out first and reactants that remain after the reaction?

Accepted Answer

Reactants that run out first are limiting reactants, while reactants that remain are excess reactants.

Answer

Reactants with smaller atoms are limiting reactants, while reactants with larger atoms are excess reactants.

Answer

Reactants that react more quickly are limiting reactants, while reactants that react more slowly are excess reactants.

Answer

Reactants that are not necessary for the reaction are limiting reactants.

Question 49

During a chemical reaction, what do scientists call the substances that undergo change?

Accepted Answer

Reactants

Answer

Participants

Answer

Elements

Answer

Products

Question 50

Which of the following is an element?

Accepted Answer

Gold

Answer

Water

Answer

Salt

Answer

Carbon dioxide

Question 51

What is the smallest unit of an element that can exist?

Accepted Answer

Atom

Answer

Molecule

Answer

Ion

Answer

Neutron

Question 52

What is the name of the table that groups together all known elements?

Accepted Answer

Periodic table

Answer

Atomic table

Answer

Element table

Answer

Chemical table

Question 53

Which of the following is a metal?

Accepted Answer

Iron

Answer

Oxygen

Answer

Carbon

Answer

Hydrogen

Question 54

What is the symbol for the element sodium?

Accepted Answer

Na

Answer

So

Answer

Sd

Answer

Sm

Question 55

What is the name of the bond formed when two atoms share electrons?

Accepted Answer

Covalent bond

Answer

Ionic bond

Answer

Metallic bond

Answer

Hydrogen bond

Question 56

Which of the following is an acid?

Accepted Answer

Hydrochloric acid

Answer

Sodium hydroxide

Answer

Sodium chloride

Answer

Water

Question 57

What is the chemical symbol for sodium?

Accepted Answer

Na

Answer

So

Answer

Sd

Answer

Sm

Question 58

Which group in the periodic table contains elements that are highly reactive and form salts?

Accepted Answer

Alkali metals

Answer

Halogens

Answer

Noble gases

Answer

Transition metals

Question 59

Which of these is an example of a chemical change?

Accepted Answer

Burning wood

Answer

Melting ice

Answer

Dissolving sugar in water

Answer

Folding a piece of paper

Question 60

What are the positively charged particles in an atom called?

Accepted Answer

Protons

Answer

Neutrons

Answer

Electrons

Answer

Quarks

Question 61

Which of these represents a balanced chemical equation?

Accepted Answer

2H2 + O2 -> H2O

Answer

2H2 + O -> H2O

Answer

H2 + 2O -> H2O

Answer

H2O -> H2 + O

Question 62

What is the term for when a solid directly transforms into a gas without becoming a liquid?

Accepted Answer

Sublimation

Answer

Condensation

Answer

Evaporation

Answer

Melting

Question 63

What is the function of a catalyst?

Accepted Answer

To speed up a chemical reaction

Answer

To slow down a chemical reaction

Answer

To be produced in a chemical reaction

Answer

To be consumed in a chemical reaction

Question 64

Why is measuring pH important in chemistry?

Accepted Answer

It indicates whether a substance is acidic, neutral, or alkaline.

Answer

It determines the strength of an acid or base.

Answer

It is only used in scientific labs.

Answer

It has no practical applications.