Wayground
CFE Review: Law of Conservation of Mass and Energy - Printable Science Worksheets 8th Grade - Wayground

CFE Review: Law of Conservation of Mass and Energy

Veronica Renuart

Created by Veronica Renuart

20 questions

8th Grade

Science

Updated Sept 2026

CFE Review: Law of Conservation of Mass and Energy is a free printable Grade 8 physics worksheet with 20 multiple-choice questions and a complete answer key. It reviews the law that mass and matter are not created or destroyed, including conservation during chemical reactions and physical changes, the need to account for gases, and evidence that a chemical reaction has occurred. Students also use given masses to reason about gas produced during a reaction. The worksheet then connects conservation to energy. Students identify that energy cannot be created or destroyed, recognize chemical-to-kinetic and chemical-to-heat-to-electrical transformations, classify running as kinetic energy, and identify mechanical and electrical energy in a wind turbine. Questions about where potential and kinetic energy are highest reinforce how energy changes with motion and position. This review format is suited to Grade 8 science instruction, independent practice, or assessment after teaching work and energy.

Worksheet settings

Font size

S
M
L
XL
WaygroundWorksheets

CFE Review: Law of Conservation of Mass and Energy

Total questions: 20

Name
Class
Date
1.
What is the Law of Conservation of mass?
a)
Mass is created in a chemical reaction
b)
Mass is created in a physical change
c)
New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
d)
Mass is never created or destroyed
2.
What will weigh more when a chemical change is complete?  The reactants before the chemical reaction, or the product after the reaction is complete?
a)
They both will weigh the same
b)
The product always weighs more than the reactant
c)
The reactant will weigh more than the product
d)
They both will loose mass after the reaction
3.
Since gasses weigh nothing, when they are produced in a reaction they do not have to be accounted for.  
a)
True
b)
False
4.
Which are chemical changes
a)
Iron rusting 
b)
Glass breaking
c)
Clothing ripping
d)
Hair cut
5.
Can matter be created or destroyed?
a)
Yes, it can be created.
b)
Yes, it can be destroyed.
c)
No, matter is always conserved
d)
None of these
6.
The mass after a physical change, such as ice melting into water, stays the same
a)
True
b)
False
7.
Evidence of a chemical reaction include:
a)
Phase change
b)
No new substance
c)
Bubbles forming
d)
Shape change
8.
10 g of a solid chemical reacts with a 10 g of a liquid chemical, the reaction bubbles and changes the color of the liquid.  The colored liquid weighs 13 g, what can be concluded?
a)
The gas produced from the bubbles weighed 5 g
b)
The bubbles were evidence of 7 g of matter being destroyed
c)
The gas produced weighed 7 g
d)
The gas produced weighed 13 g
9.
The Law of Conservation of Energy states:
a)
Energy can created or destroyed but not transformed 
b)
Energy cannot be created or destroyed, it can only transformed
c)
Energy can't be created, destroyed or transformed
10.
Which energy transformation below matches?
Animals eating food?
a)
electrical to potential
b)
chemical to kinetic
c)
potential to chemical
11.
Which energy transformation below matches?
Burning coal or carbon-based fuel at a powerplant?
a)
chemical to heat to electrical
b)
mechanical to chemical to sound
c)
electrical to chemical to heat
12.
Potential or kinetic?
Running?
a)
potential
b)
kinetic
13.
What kind of energy does a wind turbine contain and produce?
a)
Mechanical and Electrical
b)
Potential
c)
Nuclear
d)
Chemical and Mechanical
14.
Where is potential energy the highest?
Where is potential energy the highest?
a)
W 
b)
X
c)
Y
d)
Z
15.
Where is kinetic energy the highest?
Where is kinetic energy the highest?
a)
W 
b)
X
c)
Y
d)
Z
16.
Energy due to motion is ____________ energy. 
a)
Potential 
b)
Energy
c)
Kinetic
d)
Friction
17.
__________ is stored energy. 
a)
Potential
b)
Kinetic
c)
None of the above 
d)
All of the above 
18.
What kind of energy is represented in this picture?
What kind of energy is represented in this picture?
a)
Thermal
b)
Potential
c)
Nuclear
d)
Mechanical
19.
Which of the following is NOT an example of chemical change?
a)
sour milk
b)
burning wood
c)
breaking a pencil
d)
rust
20.
A change in the size, shape, or state of matter.
a)
chemical change
b)
physical change
c)
chemical reaction
d)
electron change
WaygroundAnswer Key

CFE Review: Law of Conservation of Mass and Energy

Total questions: 20

1.
d) Mass is never created or destroyed
2.
a) They both will weigh the same
3.
b) False
4.
a) Iron rusting 
5.
c) No, matter is always conserved
6.
a) True
7.
c) Bubbles forming
8.
c) The gas produced weighed 7 g
9.
b) Energy cannot be created or destroyed, it can only transformed
10.
b) chemical to kinetic
11.
a) chemical to heat to electrical
12.
b) kinetic
13.
a) Mechanical and Electrical
14.
a) W 
15.
b) X
16.
c) Kinetic
17.
a) Potential
18.
a) Thermal
19.
c) breaking a pencil
20.
b) physical change

Browse by subjects

Browse by grades

Browse by format

FAQs

What does this worksheet cover, and how does it help students learn conservation of mass and energy?

This Grade 8 worksheet uses 20 multiple-choice questions to assess conservation of mass in physical and chemical changes, including accounting for gases and interpreting mass data from a reaction. It also asks students to apply conservation of energy by identifying energy transformations, distinguishing potential from kinetic energy, and recognizing the energy forms associated with a wind turbine.

How can I use this worksheet to teach the law of conservation of mass and energy?

Use the mass questions to have students compare reactants and products, then discuss why gas produced in a bubbling reaction must be included in the total mass. Follow with the energy questions by asking students to trace transformations such as chemical energy to kinetic energy in animals and chemical energy to heat to electrical energy in a power plant. Students can explain their choice for each multiple-choice item before completing the review independently.

What mistakes should I watch for when students complete this conservation of mass and energy worksheet?

Students may incorrectly treat gases as weightless, assume a chemical reaction destroys mass, or confuse a physical change such as melting with a chemical change such as rusting. They may also reverse energy transformations, select potential energy for running instead of kinetic energy, or overlook that the gas in the reaction-mass problem accounts for the difference between the starting and final masses.

How do I assign and grade this worksheet?

The worksheet is available as a printable PDF and as a digital quiz on Wayground, so you can assign the 20 multiple-choice questions in the format that fits your class. It includes a complete answer key, and printable submissions can be graded by scanning student work with the Wayground for Teachers app. The printable option can also support schools that are reducing screen time.

How does this worksheet practice identifying energy transformations?

Several multiple-choice items require students to match real examples with the correct energy pathway, including animals eating food and burning coal at a power plant. Other items ask students to classify running as kinetic energy and identify the mechanical and electrical energy associated with a wind turbine, helping them apply conservation of energy to familiar systems.

Where can I find more worksheets like this on Wayground?

Wayground offers a comprehensive collection of free printable worksheets and practice problems across all subjects, with downloadable PDFs and answer keys to help students master essential skills and concepts. Browse more resources at https://wayground.com/en-us/worksheets.

© 2026 Wayground Inc.

Accessibility and Inclusion