Quiz about Chemistry Unit Test - 2025

Question 1

The picture shows an isotope of an element. Based on the information in the periodic table, which element is shown in the picture?

Accepted Answer

<ul><li>carbon (C)</li><li></li></ul>

Answer

<ul><li></li><li>boron (B)</li><li></li><li></li></ul>

Answer

lithium (Li)

Answer

helium (He)

Question 2

Liam explores the decomposition of water. He attaches a battery to the ends of two pencils sharpened at both ends, and places the other ends of the pencils in a beaker of water. His set up is shown below.
Liam knows that some of the bubbles in his experiment must be oxygen. He draws an atomic model of the element oxygen. What does he include in his drawing? Select all that apply.

Accepted Answer

eight protons in the nucleus

Accepted Answer

eight electrons outside of the nucleus

Accepted Answer

eight neutrons in the nucleus

Answer

sixteen protons in the nucleus

Answer

sixteen electrons outside of the nucleus

Question 3

Darnell draws a picture of a nitrogen atom. He draws a small circle to represent the nucleus and draws dots around the circle to represent the electrons. How many dots does he draw?

Accepted Answer

7 dots

Answer

5 dots

Answer

14 dots

Answer

16 dots

Question 4

Bernice draws an oxygen atom. She draws a small circle for the nucleus. Inside of the circle, she draws plus signs for protons and dots for neutrons. Around the nucleus she uses minus signs to represent electrons. Which statements are true about her drawing? Select ALL that apply.

Accepted Answer

There are eight protons in the nucleus.

Accepted Answer

There are eight neutrons in the nucleus.

Answer

There are sixteen protons in the nucleus.

Answer

There are sixteen neutrons in the nucleus.

Answer

There are sixteen electrons in her drawing.

Question 5

Using information from the periodic table, which diagram shows a correct model for an atom of neon?

Accepted Answer

Question 6

Pure Substances and Mixtures

Two categories of substances are pure substances and mixtures.

Pure substances have a constant chemical composition and chemical properties. Elements and compounds are examples of pure substances. Elements consist of one or more of one type of atom and are not chemically bonded. Compounds consist of two or more types of elements that are held together with a chemical bond.

Mixtures contain two or more different substances that are not held together with a chemical bond. Two types of mixtures are homogeneous and heterogeneous mixtures. Homogeneous mixtures have a uniform composition throughout the mixture, while heterogenous mixtures do not.

A student develops models of pure substances and mixtures using different colors of balls and plastic sticks. A key for each element and chemical bond is shown.

A model of a substance in a container is shown. Which best identifies the type of substance in the container?

Accepted Answer

heterogeneous mixture

Answer

element

Answer

compound

Answer

homogeneous mixture

Question 7

Pure Substances and Mixtures

Two categories of substances are pure substances and mixtures.

Pure substances have a constant chemical composition and chemical properties. Elements and compounds are examples of pure substances. Elements consist of one or more of one type of atom and are not chemically bonded. Compounds consist of two or more types of elements that are held together with a chemical bond.

Mixtures contain two or more different substances that are not held together with a chemical bond. Two types of mixtures are homogeneous and heterogeneous mixtures. Homogeneous mixtures have a uniform composition throughout the mixture, while heterogenous mixtures do not.

A student develops models of pure substances and mixtures using different colors of balls and plastic sticks. A key for each element and chemical bond is shown.

Which description of the substance best supports the choice from Part A?

Accepted Answer

There is not a uniform composition throughout.

Answer

The substance consists of one type of atom.

Answer

All substances in the container are chemically bonded.

Answer

There is a uniform composition throughout.

Question 8

Pure Substances and Mixtures

Two categories of substances are pure substances and mixtures.

Pure substances have a constant chemical composition and chemical properties. Elements and compounds are examples of pure substances. Elements consist of one or more of one type of atom and are not chemically bonded. Compounds consist of two or more types of elements that are held together with a chemical bond.

Mixtures contain two or more different substances that are not held together with a chemical bond. Two types of mixtures are homogeneous and heterogeneous mixtures. Homogeneous mixtures have a uniform composition throughout the mixture, while heterogenous mixtures do not.

A student develops models of pure substances and mixtures using different colors of balls and plastic sticks. A key for each element and chemical bond is shown.

Which two are examples of elements?

Accepted Answer

nitrogen (N)

Accepted Answer

hydrogen (H)

Answer

Hydrochloric Acid (HCl)

Answer

water (H₂O)

Answer

ammonia (NH₃)

Question 9

Which 2 are not pure substances and are mixtures?

Accepted Answer

Accepted Answer

Question 10

Elements, compounds, and mixtures.

A student performs three experiments.

In the first experiment, the student combines iron filings and sulfur powder in a dish. The student holds a magnet over the dish and observes that the iron filings are attracted to the magnet. The student's set up and observation are shown.

In the second experiment, the student combines iron filings and sulfur powder in a test tube. The iron filings and sulfur powder are heated until iron sulfide is formed. After cooling, the student holds the magnet over the test tube. The magnet does not attract the iron filings. The set up and observation are shown.

In the third experiment, the student uses two beakers of water. To one beaker, a tablespoon of sugar is added and stirred. The resulting solution is uniform throughout. To the other beaker, a tablespoon of oil is added and stirred. The resulting solution does not have a uniform composition. Both beakers are shown before and after.

Which statement best describes the iron sulfide that forms in Experiment 2?

Accepted Answer

It is a compound formed through a chemical reaction.

Answer

It is an element formed through a chemical reaction.

Answer

It is a homogeneous mixture formed through a physical change.

Answer

It is a heterogenous mixture formed through a physical change.

Question 11

Elements, compounds, and mixtures.

A student performs three experiments.

In the first experiment, the student combines iron filings and sulfur powder in a dish. The student holds a magnet over the dish and observes that the iron filings are attracted to the magnet. The student's set up and observation are shown.

In the second experiment, the student combines iron filings and sulfur powder in a test tube. The iron filings and sulfur powder are heated until iron sulfide is formed. After cooling, the student holds the magnet over the test tube. The magnet does not attract the iron filings. The set up and observation are shown.

In the third experiment, the student uses two beakers of water. To one beaker, a tablespoon of sugar is added and stirred. The resulting solution is uniform throughout. To the other beaker, a tablespoon of oil is added and stirred. The resulting solution does not have a uniform composition. Both beakers are shown before and after.

Which statement best supports that iron sulfide is a compound formed through a chemical reaction.

Accepted Answer

Iron sulfide has different properties than iron and sulfur and cannot be separated through physical means.

Answer

Iron sulfide has the same properties as iron and sulfur and can be easily separated.

Answer

Iron sulfide has the same composition as iron and sulfur and can be easily separated.

Answer

Iron sulfide has a different temperature than iron and sulfur and cannot be separated through physical means.

Question 12

Elements, compounds, and mixtures.

A student performs three experiments.

In the first experiment, the student combines iron filings and sulfur powder in a dish. The student holds a magnet over the dish and observes that the iron filings are attracted to the magnet. The student's set up and observation are shown.

In the second experiment, the student combines iron filings and sulfur powder in a test tube. The iron filings and sulfur powder are heated until iron sulfide is formed. After cooling, the student holds the magnet over the test tube. The magnet does not attract the iron filings. The set up and observation are shown.

In the third experiment, the student uses two beakers of water. To one beaker, a tablespoon of sugar is added and stirred. The resulting solution is uniform throughout. To the other beaker, a tablespoon of oil is added and stirred. The resulting solution does not have a uniform composition. Both beakers are shown before and after.

The student wants to draw a model to represent the iron filings and sulfur powder after they are combined in Experiment 1. Which model would the student MOST LIKELY draw?

Accepted Answer

Question 13

Four molecule models are shown.

Water is composed of two hydrogen atoms and one oxygen atom. Which model most likely contains only water?

Accepted Answer

Model 3

Answer

Model 1

Answer

Model 2

Answer

Model 4

Question 14

Which are 2 examples of elemental molecules?

Accepted Answer

Model 1

Accepted Answer

Model 4

Answer

Model 2

Answer

Model 3

Question 15

Which 2 are compound molecules?

Accepted Answer

Model 2

Accepted Answer

Model 3

Answer

Model 1

Answer

Model 4

Question 16

The table shows several substances used in a science experiment. Use the table to answer the questions that follow.

Which substances are elements?

Accepted Answer

Question 17

The table shows several substances used in a science experiment. Use the table to answer the questions that follow.

Select all of the substances that are created by combining different kinds of atoms.

Accepted Answer

Accepted Answer

Accepted Answer

Question 18

What statement is true about the eight elements on the periodic table termed metalloids?

Accepted Answer

They have properties of both metals and nonmetals.

Answer

They are the only man-made elements.

Answer

They all have the same number of protons and neutrons.

Answer

They are the only naturally occurring elements.

Question 19

Carlos knows atoms of hydrogen (H) and oxygen (O) can combine to make water. He draws four possible models of a water molecule. Based on the information from the periodic table, which of his models is correct?

Accepted Answer

Question 20

The periodic table is organized into vertical groups of

Accepted Answer

elements with similar properties.

Answer

compounds with different properties.

Answer

elements with different properties.

Answer

compounds with similar properties.

Question 21

A majority of the 118 elements on the periodic table are classified as

Accepted Answer

metals

Answer

liquids.

Answer

metalloids

Answer

non-metals.

Question 22

Which of following explains the location of oxygen on the periodic table?

Accepted Answer

It has one more proton than nitrogen, so it is located after nitrogen, and it is a non-metal, so it located on the right side of the periodic table.

Answer

It has one more proton than nitrogen, so it is located after nitrogen, and it is a metal, so it is located on the right side of the periodic table.

Answer

It has one less proton than nitrogen, so it is located after nitrogen, and it is a non-metal, so it is located on the right side of the periodic table.

Answer

It has one less proton than nitrogen, so it is located after nitrogen, and it is a metal, so it is located on the right side of the periodic table.

Question 23

When sodium is mixed with water, an explosion takes place. Based on its location on the periodic table, how will potassium behave with water?

Accepted Answer

Potassium, which shares similar properties with sodium, will explode in water.

Answer

Potassium, which shares similar properties with sodium, will not explode in water.

Answer

Potassium, which does not share similar properties with sodium, will explode in water.

Answer

Potassium, which does not share similar properties with sodium, will not explode in water.

Question 24

The elements on the periodic table are arranged according to increasing atomic number. The elements are arranged in horizontal rows called periods and vertical columns called groups. Elements in the same group behave similarly in chemical reactions because they have similar properties.

Which list of elements will behave similarly in a chemical reaction?

Accepted Answer

hydrogen, lithium, potassium

Answer

lithium, aluminum, oxygen

Answer

potassium, bromine, krypton

Answer

sodium, magnesium, aluminum

Question 25

Zinc and Hydrochloric Acid

A teacher wearing a lab coat and safety goggles conducts an experiment under a vent hood in a chemistry laboratory. The students observe and take notes. In the experiment, the teacher drops discs of zinc (Zn) into a flask of liquid hydrochloric acid (HCl). The students record that the mass of the substances before the reaction occurs is 262 grams. They also record the temperature of the substances and the fact that both zinc and hydrochloric acid are not flammable. Before the reaction begins, the zinc is placed into a balloon attached to the top of a flask containing the hydrochloric acid. This seals the flask before the reaction takes place. To initiate the reaction, the zinc is dropped into the hydrochloric acid. As soon as the substances combine, bubbles begin to form, and the balloon expands. The picture shows the zinc as it is dropped into the flask, and the reaction as it is taking place.

After the reaction takes place, the temperature of the flask is recorded. The students note that the temperature of the flask is higher than before the reaction took place. The teacher then removes the balloon from the flask and carefully ignites the balloon in front of the class. The students record that the substance in the balloon was flammable.

Which statement BEST interprets the temperature change that occurred in the experiment?

Accepted Answer

When the substances were combined, the chemical reaction released heat.

Answer

Reactions that include zinc discs release heat.

Answer

Reactions that include hydrochloric acid release heat.

Answer

When the substances were combined, the physical change released heat.

Question 26

Zinc and Hydrochloric Acid

A teacher wearing a lab coat and safety goggles conducts an experiment under a vent hood in a chemistry laboratory. The students observe and take notes. In the experiment, the teacher drops discs of zinc (Zn) into a flask of liquid hydrochloric acid (HCl). The students record that the mass of the substances before the reaction occurs is 262 grams. They also record the temperature of the substances and the fact that both zinc and hydrochloric acid are not flammable. Before the reaction begins, the zinc is placed into a balloon attached to the top of a flask containing the hydrochloric acid. This seals the flask before the reaction takes place. To initiate the reaction, the zinc is dropped into the hydrochloric acid. As soon as the substances combine, bubbles begin to form, and the balloon expands. The picture shows the zinc as it is dropped into the flask, and the reaction as it is taking place.

After the reaction takes place, the temperature of the flask is recorded. The students note that the temperature of the flask is higher than before the reaction took place. The teacher then removes the balloon from the flask and carefully ignites the balloon in front of the class. The students record that the substance in the balloon was flammable.

Did a chemical reaction take place? Explain why or why not.

Accepted Answer

Yes, because the reactants were not flammable, but the gaseous product was flammable

Answer

No, because neither the reactants nor the liquid product were flammable

Answer

No, because the mass in the flask appears to change when the reaction takes place

Answer

Yes, because the mass in the flask appears to be the same both before and after the reaction took place

Question 27

Zinc and Hydrochloric Acid

A teacher wearing a lab coat and safety goggles conducts an experiment under a vent hood in a chemistry laboratory. The students observe and take notes. In the experiment, the teacher drops discs of zinc (Zn) into a flask of liquid hydrochloric acid (HCl). The students record that the mass of the substances before the reaction occurs is 262 grams. They also record the temperature of the substances and the fact that both zinc and hydrochloric acid are not flammable. Before the reaction begins, the zinc is placed into a balloon attached to the top of a flask containing the hydrochloric acid. This seals the flask before the reaction takes place. To initiate the reaction, the zinc is dropped into the hydrochloric acid. As soon as the substances combine, bubbles begin to form, and the balloon expands. The picture shows the zinc as it is dropped into the flask, and the reaction as it is taking place.

After the reaction takes place, the temperature of the flask is recorded. The students note that the temperature of the flask is higher than before the reaction took place. The teacher then removes the balloon from the flask and carefully ignites the balloon in front of the class. The students record that the substance in the balloon was flammable.

Which statement BEST explains why the gas in the balloon was flammable, but the reactants were not?

Accepted Answer

The atoms of the reactants were rearranged into a new substance with new chemical properties.

Answer

Atoms were created when the reaction took place, which resulted in the appearance of a flame.

Answer

Atoms were destroyed when the reaction took place, which resulted in the appearance of a flame.

Answer

The atoms of the reactants were rearranged into a new substance with new physical properties.

Question 28

The students in Ms. Ramirez's science class are classifying different types of reactions. They have divided the reactions into two columns, as shown below.

Why are the reactions listed in Column B classified as physical reactions?

Accepted Answer

The materials maintained their original properties.

Answer

They produced new substances with different properties.

Answer

They released heat during the reactions.

Answer

The reactions are irreversible.

Question 29

The students in Ms. Ramirez's science class are classifying different types of reactions. They have divided the reactions into two columns, as shown below.

Why are the reactions listed in Column A classified as chemical reactions?

Accepted Answer

They changed the properties of the materials irreversibly.

Answer

The changes do not affect the materials' characteristics.

Answer

The changes to the materials can be easily reversed.

Answer

They changed the shape of the materials.

Question 30

Liam explores the decomposition of water. He attaches a battery to the ends of two pencils sharpened at both ends, and places the other ends of the pencils in a beaker of water. His set up is shown below.

Liam notices that bubbles form under the water at each pencil tip. What type of change is happening?

Accepted Answer

a chemical change

Answer

no change

Answer

a nuclear change

Answer

a physical change

Question 31

The diagram shows a test tube of copper (II) sulfate solution before and after the addition of iron shavings during an experiment.

The experiment shows a

Accepted Answer

chemical reaction, because the solution unexpectedly changed color.

Answer

physical reaction, because it involved a compound.

Answer

physical reaction, because the solution changed color.

Answer

chemical reaction, because it involved a mixture.

Question 32

Water Formation

Water (H₂O) is a compound required for survival by living organisms. The diagram below shows the chemical reaction of hydrogen gas (H₂) with oxygen gas (O₂) to form water (H₂O).

Choose the statement that BEST compares the mass of the products to the mass of the reactants.

Accepted Answer

The number of hydrogen atoms and oxygen atoms is the same before and after the reaction, so the mass does not change during the reaction.

Answer

The number of hydrogen atoms and oxygen atoms changes during the reaction, so the mass changes during the reaction.

Answer

The number of hydrogen atoms and oxygen atoms changes during the reaction, but the mass does not change during the reaction.

Answer

The number of hydrogen atoms and oxygen atoms is the same before and after the reaction, but the mass changes during the reaction.

Question 33

Three students were working together in the science lab at school. They wanted to investigate how different types of changes affect the mass of substances. They each planned to use different activities in their investigation.

Activity 1
One student places a beaker on a laboratory scale and adds 250 milliliters of water. He then adds 50 grams of sugar to the beaker and stirs until the solution is clear.

Activity 2
Another student places a bowl on a laboratory scale and puts some ice cubes into the bowl. She leaves the bowl of ice cubes on the scale for 15 minutes.

Activity 3
A third student places two flasks on a laboratory scale. Next, she adds 20 g of baking soda into one flask and 50 g of acetic acid into the other flask. She then pours the acetic acid into the flask that contains the baking soda.

Which graph represents the total mass of the substances before and after they are stirred together in Activity 1?

Accepted Answer

Question 34

A stack of newspapers is burned completely to ash in a laboratory. How does the resulting mass relate to the initial mass of the stack of newspapers?

Accepted Answer

The mass of the gases and the ash should equal the mass of the initial stack of newspapers.

Answer

The mass of the gases and the ash should be one-fourth the mass of the initial stack of newspapers.

Answer

The mass of the gases and the ash should be one-half the mass of the initial stack of newspapers.

Answer

The mass of the gases and the ash should be double the mass of the initial stack of newspapers.

Chemistry Unit Test - 2025

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