WorksheetsL2 Matter Review
Total questions: 130
Worksheet time: 1hrs 5mins
Which phrase best describes a chemical reaction?
A change in shape only
A movement of particles only
A rearrangement without change
A process forming new substances
During a chemical reaction, what happens to the properties of the substances involved?
They become physical changes
They always stay identical
They never change at all
They often change noticeably
Which observation most likely indicates a chemical change has occurred?
Formation of gas bubbles
Melting a solid object
Breaking a large rock
Water freezing into ice
Which statement about reactants and products is true?
Reactants are always gases
Products turn into reactants
Products are always liquids
Reactants turn into products
Which change is usually a physical change, not a chemical change?
Water evaporating into vapor
Iron rusting in moist air
Baking batter into cake
Vinegar reacting with baking soda
Why does rusting show a property change?
Iron becomes magnetized
Iron forms a new substance
Iron changes only shape
Iron cools down slightly
A closed container shows mass staying constant during a reaction. What principle does this illustrate?
Electrical neutrality
Expansion of gases
Conservation of mass
Conservation of energy only
When wood burns, which evidence supports that a chemical reaction occurred?
The wood turns transparent
The wood becomes wet
The wood is cut smaller
Ash and gases are formed
Which scenario best matches a chemical property being tested?
Checking water temperature
Adding acid to metal
Weighing a backpack
Measuring block length
Which outcome shows products have different properties than reactants?
Hard cake formed from liquid batter
Ice formed from liquid water
Crushed cans from metal sheets
Dissolved sugar in warm tea
Which statement best defines a chemical change?
Particles move faster but stay the same substance
A change in matter that makes a new substance
A reversible change that keeps the substance
Matter changes shape without new substance forming
What does a chemical change affect in a substance?
Its identity becomes a new substance
Its temperature always decreases
Its phase always becomes a gas
Its size becomes much smaller
Which example shown is a chemical change?
Iron rusting in moist air
Sugar dissolving in tea
Ice melting on a plate
Water boiling in a pot
Burning wood is classified as which type of change?
Chemical change making new substances
Mechanical change altering shape only
Physical change with no new substance
Phase change forming only water vapor
Cooking an egg results in what outcome?
Only temperature increases then cools
A new substance forms from proteins
Shell softens without chemical change
Proteins reshape but remain raw egg
Which situation most clearly shows a new substance forming?
Aluminum being cut into pieces
Salt crystals forming from water
Water freezing into ice cubes
Banana turning brown and soft
When vinegar reacts with baking soda, what evidence suggests a chemical change?
Becoming a clear solution
Cooling to room temperature
Formation of bubbles from gas
Settling of solid crystals
Which process is least likely to be reversed easily?
Melting butter on toast
Baking a cake in an oven
Condensing steam on glass
Stretching a rubber band
Electroplating mainly demonstrates what?
A chemical change creating a coating
A mechanical change increasing speed
A physical change removing mass
A phase change from liquid to gas
Fireworks display colors due to which type of change?
Mechanical change breaking shells open
Chemical reactions producing light and gas
Physical change releasing pigments only
Phase change turning solid to liquid
Which observation is a sign that a chemical change may be occurring in a liquid sample?
Surface becomes smoother and clearer
Formation of bubbles throughout the liquid
Container feels slippery when touched
Liquid level slowly evaporates over days
A student mixes two clear solutions and the mixture suddenly becomes warmer. What does this unexpected temperature change suggest?
Heat from room lights only
A physical change like dissolving
Measurement error with the thermometer
A chemical reaction releasing energy
Which change in color best indicates a chemical change rather than a simple mixing?
Color looks different through tinted glass
The liquid looks darker due to shadows
Unexpected color appears after mixing
Color seems brighter under sunlight
Which observation most directly suggests a new substance formed during a reaction?
The liquid swirls faster when stirred
The solution level rises slightly
The container becomes heavier to hold
A solid precipitate appears in the mixture
Which statement about odor helps identify a chemical change?
Different people describe the smell differently
The smell seems stronger up close
A new, unusual smell develops during mixing
Smell fades when the lid is closed
Combustion is a sign of chemical change. Which scenario shows combustion?
A substance cracks from drying out
A substance cools and becomes solid
A substance burns producing light and heat
A substance melts into a liquid phase
A student adds powder to water and sees fizzing and gas bubbles. Which claim is best supported?
A gas is produced by a chemical reaction
Only a physical change like dissolving occurred
The bubbles are trapped air from stirring
The powder increased water’s density only
Two solutions are mixed, and a cloudy solid forms and settles. What is this solid called?
Sediment from dirty glassware
Ice produced by cooling
Crystal from slow evaporation
Precipitate formed during reaction
Which pair of observations together most strongly indicates a chemical change?
Brighter light and cleaner glass
Higher volume and faster stirring
Unexpected color and new odor
Lower mass and slower pouring
A teacher asks how to know when a new type of matter has formed. Which answer lists valid signs?
Bubbles, temperature change, precipitate
Shadows, reflections, brightness
Evaporation, freezing, condensation
Stretching, folding, bending
Which observation is a sign that a chemical change has occurred in fruit left out for days?
The shape turns more round
The skin gets a little softer
The fruit feels slightly colder
The odor becomes sour and strong
In autumn, many leaves change color. What does this color change indicate?
A temperature change only
A mixing of soil and water
A physical change from wind
A chemical change in leaf pigments
Which event most clearly shows a chemical reaction releasing energy as light and heat?
Fireworks exploding at night
A balloon slowly deflating
Water freezing in winter
Sugar dissolving in tea
When an antacid tablet is mixed with water, bubbles appear. What do the bubbles show?
Gas produced by a chemical reaction
Air trapped by stirring motion
Tablet shrinking due to melting
Water temperature increasing only
Which observation best distinguishes a chemical change from a physical change?
Increase in speed only
Movement from one place
Change in object’s size
Formation of a new substance
A student says leaf color changes because the leaf breaks into smaller pieces. What is the best correction?
Pieces increase surface area only
Color change comes from new substances
Wind scratches the leaf surface
Leaf absorbs more water then
If fruit odor changes as it rots, which statement explains why the smell is different?
Color becomes brighter
Seeds become drier
Water evaporates quickly
New molecules are formed
Which situation would NOT be evidence of a chemical reaction?
Ice melting into liquid water
Leaves turning red in fall
Fireworks producing bright flames
Antacid fizzing in water
A science fair display shows fizzing, temperature change, and color change. Which claim is supported by these signs?
Only physical changes occurred
Gas pressure stayed constant
A chemical reaction occurred
No changes happened
You drop an antacid into water to reduce stomach acid. Why does fizzing help the tablet work?
The bubbles push the tablet upward
The tablet absorbs water and swells
The water cools and dissolves only
The reaction forms gas and new substances
Which statement best describes what happens to matter during a chemical change?
Matter disappears completely into energy
Matter is created from nothing new
Matter is rearranged into new substances
Matter stays exactly the same form
According to the law of conservation of mass, the total mass before a reaction compared to after the reaction is
greater before than after
less before than after
the same before and after
unknown without a scale
Two substances react in a closed container. What should be true if you measure their masses before and after?
Total mass decreases slightly
Total mass remains the same
Total mass doubles unexpectedly
Total mass increases slightly
In the image showing molecules before and after a reaction, what changes?
The type of elements present
The arrangement of atoms in molecules
The number of atoms in total
The mass of each atom itself
Which phrase correctly defines the Law of Conservation of Mass?
Matter can be created or destroyed freely
Matter cannot be created or destroyed
Matter changes mass during reactions
Matter always becomes energy only
A student claims mass is converted during chemical changes. Which correction is most accurate?
Mass is destroyed during reactions
Mass is created during reactions
Mass is conserved during reactions
Mass becomes heavier after reactions
You combine 20 g of substance A with 30 g of substance B. After the reaction, what total mass should you measure?
60 grams total
50 grams total
55 grams total
45 grams total
Why do scientists often measure reactant and product masses in experiments?
To check color changes only
To test conservation of mass
To find brand names of chemicals
To see if atoms vanish
Which situation would violate the law of conservation of mass in a closed system?
Products totaling less mass than reactants
Reactants rearranging into new molecules
Products totaling the same mass as reactants
Atoms staying the same elements overall
A reaction shows three white atoms and two red atoms before, and different groupings after. What conclusion fits best?
Atoms lost their mass during reaction
Atoms rearranged into new combinations
Atoms multiplied without cause
Atoms changed into different elements
Which statement best describes particle motion in matter shown in the diagram?
Particles in matter move only in straight lines
Particles in matter move only when heated
Particles in matter stay completely still
Particles in matter move constantly
What happens when moving particles collide with enough force?
Bonded atoms can break apart
Molecules freeze instantly
Atoms become heavier and larger
Atoms lose all electrons forever
During a chemical change, after bonds break, what do atoms do next?
Fuse into a single giant atom
Return to their original molecule unchanged
Stop moving and remain separate
Rearrange and bond with other atoms
Which phrase correctly completes the sequence: move → collide → ______ → rearrange?
break apart
cool down
expand outward
absorb light
Which choice identifies a chemical change illustrated in the image?
Atoms forming new bonds with different partners
Particles spreading farther apart without bonding
A molecule changing shape but remaining the same
Atoms slowing down while staying bonded
Why do collisions between particles sometimes cause chemical reactions?
Collisions remove atoms from matter
Low-energy collisions always make bonds
High-force collisions can break bonds
Collisions stop atoms from moving
Which event in the diagram signals the moment a bond breaks?
The small gray spheres move left
The arrow points to the right
The burst icon appears at impact
The red molecule rotates slightly
Select the best explanation for “rearrange” in a chemical reaction.
Atoms change partners to form new molecules
Atoms spin faster but stay in place
Molecules stretch without losing bonds
Particles move randomly with no changes
Which outcome is most likely if particles collide without enough force?
Atoms remain bonded in the original molecules
Atoms instantly fuse into a new element
All atoms become charged ions
Particles disappear from the system
Which statement aligns with the idea of constant motion in matter?
Even in solids, particles vibrate continuously
Solids have particles that never move
Only gases have moving particles at room temperature
Liquids have particles that never collide
Which statement best defines a chemical reaction?
Particles spread out but stay chemically the same
Matter changes shape while atoms remain unchanged
Atoms rearrange to make one or more new substances
Molecules separate without forming any new substances
In a chemical reaction, what are reactants?
Catalysts that speed up the change
Energy released during the change
Starting substances that undergo the change
Final substances formed after the change
In a chemical reaction, what are products?
Tools used to measure the chemical change
Substances that start the chemical change
Heat absorbed before the chemical change
Substances produced by the chemical change
Which change is most likely a chemical reaction?
Iron rusting on a wet fence
Water freezing in winter
Ice melting in a cup
Sugar dissolving in tea
What happens to atoms during a chemical change?
They rearrange into new combinations
They stay in the same arrangement
They disappear completely
They gain identical properties
In the equation H2 + O2 → H2O shown, which side contains the reactants?
Neither side shows reactants
Both sides equally
Right side after the arrow
Left side before the arrow
In the equation H2 + O2 → H2O, which substance is the product?
H2O on the right side
Both H2 and O2
H2 on the left side
O2 on the left side
Which phrase describes chemical changes accurately?
Often called chemical reactions
Never produce new substances
Always reversible by cooling
Always physical changes only
Why are reactants called the starting substances?
They are present before the reaction begins
They have the highest temperature always
They only exist in physical changes
They are measured after the reaction ends
A student claims products are the materials used to begin a reaction. What is the best correction?
Products are the containers holding the reaction
Products are catalysts that speed up the reaction
Products are substances made by the reaction
Products are the energy required for the reaction
Which statement best describes what happens to bonds during a chemical reaction?
Old bonds break and atoms disappear from mixtures
New bonds form but old bonds never break
Bonds break and new bonds form during reactions
Bonds stay unchanged throughout the process
In a chemical reaction, what happens to atoms overall?
Some atoms vanish into energy
Atoms rearrange but are not created or destroyed
New atoms are produced from heat
Atoms fuse into bigger single atoms
Which idea explains why all atoms at the start are present at the end of a reaction?
Law of increasing entropy
Law of conservation of atoms
Law of constant temperature
Law of magnetism in elements
In the equation CH4 + 2O2 → CO2 + 2H2O, which substance is methane?
CH4 on the left side
CO2 on the right side
2O2 on the left side
2H2O on the right side
How many oxygen molecules are required to react with one methane molecule in CH4 + 2O2 → CO2 + 2H2O?
Two oxygen molecules
Three oxygen molecules
One oxygen molecule
Four oxygen molecules
In CH4 + 2O2 → CO2 + 2H2O, what are the products?
CH4 and CO2
CO2 and 2H2O
CH4 and 2O2
O2 and H2O
Which statement about atoms in CH4 + 2O2 → CO2 + 2H2O is true?
The total number of oxygen atoms increases
Hydrogen atoms are destroyed during reaction
All atoms are conserved and rearranged
Carbon atoms split into two separate atoms
Why is the coefficient 2 placed before H2O in the products?
To show water is a reactant species
To increase the reaction speed
To indicate water has double density
To balance hydrogen and oxygen atoms
Counting atoms in CH4 + 2O2 → CO2 + 2H2O, how many hydrogen atoms are on each side?
Four on left, four on right
Four on left, two on right
Six on left, six on right
Two on left, two on right
Which change occurs in a reaction but does not violate atom conservation?
Atoms disappear after forming products
Atoms multiply without reactants present
Atoms rearrange into different molecules
Atoms become new types of elements
What do scientists use to show the substances involved in a chemical reaction?
A physical property chart
A laboratory safety poster
A chemical equation
A chemical recipe list
In a chemical equation, the substances on the left side of the arrow are called what?
Reactants
Catalysts
Products
Solvents
Which pair correctly names substances formed after a reaction takes place?
Catalysts are formed after change
Products are formed after change
Compounds are formed after change
Reactants are formed after change
Look at the diagram showing Fe2O3 + C → Fe + CO2. Which element decreases in count from reactant side to product side?
Carbon decreases from one to zero
Hydrogen decreases from two to one
Iron decreases from two to one
Oxygen decreases from three to two
In the equation Fe2O3 + C → Fe + CO2, what gas is produced?
Oxygen gas
Nitrogen gas
Carbon dioxide gas
Hydrogen gas
Which statement best describes what a chemical equation represents?
Only the energy change
Elements and compounds involved
Only the reaction temperature
The lab equipment used
If an equation shows Fe2O3 + C on the left, what name is given to Fe and CO2 on the right?
Solutions on the right
Mixtures on the right
Products on the right
Reactants on the right
Which option shows a correct matching of side and substance role?
Both sides show catalysts
Left side shows reactants
Right side shows reactants
Left side shows products
Why might scientists count atoms on each side of an equation like Fe2O3 + C → Fe + CO2?
To measure color changes quickly
To make reactions go faster
To reduce lab equipment used
To balance mass in reactions
Which item in the diagram is an element rather than a compound?
Fe2O3 on the right
Fe on the right
CO2 on the right
Fe2O3 on the left
In a chemical equation, what does the plus sign separate?
Energy from matter forms
Solids from liquids states
Atoms from molecules types
Reactants from products groups
What does the arrow in a chemical equation indicate?
Gas is produced only
The equation is balanced
Heat is added externally
A reaction has taken place
Which side lists the substances present before the reaction starts?
Reactant side of equation
Product side of equation
Middle arrow location
Balanced totals section
In the example Fe2O3 + C → Fe + CO2, which substance is a product?
Fe, the metal formed
O3, ozone molecule
Fe2O3, iron oxide
C, elemental carbon
In Fe2O3 + C → Fe + CO2, which pair are the reactants?
Fe and CO2 together
CO2 and O2 together
Fe and O2 together
Fe2O3 and C together
Choose the best description of a chemical reaction using the diagram.
Products change into reactants
Only physical changes occur
Atoms disappear in reactions
Reactants change into products
What does the diagram suggest about conservation of matter?
Atoms are rearranged, not lost
Only electrons are conserved
New atoms are created freely
Atoms vanish during reaction
Which symbol shows that substances are combined on one side of the equation?
The plus sign between terms
The equals sign at end
The minus sign before arrow
The colon next to names
If the arrow points right in an equation, what lies to the right?
Catalyst used for speed
Conditions like temperature
Reactants waiting to mix
Products formed by reaction
Which statement matches the roles of Fe2O3 and CO2 in the example?
Both are products only
Both are reactants only
Fe2O3 is a product; CO2 reactant
Fe2O3 is a reactant; CO2 a product
Which statement best explains why chemical equations must be balanced?
The number of each atom stays the same
Atoms are destroyed to make new products
Atoms can be created during reactions
Products must weigh less than reactants
In a balanced chemical equation, what must be equal on both sides?
Total number of bonds formed
Number of atoms for each element
Number of molecules overall
Amount of energy released
What law is illustrated when the number of atoms of each element is the same before and after a reaction?
Law of Increasing Entropy
Law of Conservation of Mass
Law of Constant Pressure
Law of Chemical Periodicity
Look at the diagram showing hydrogen and oxygen combining. What change balances the equation for forming water?
Use one oxygen molecule total
Use two hydrogen atoms only
Use two hydrogen molecules per oxygen
Use three oxygen atoms per molecule
Which term describes an equation where the number of atoms of each element before and after a reaction are equal?
Net ionic equation
Balanced equation
Reduced equation
Unstable equation
A student writes H2 + O2 → H2O. Why is this not balanced?
Mass of products is greater than reactants
Total atoms double after reaction
Hydrogen atoms increase after reaction
Oxygen atoms decrease after reaction
Which step helps balance a chemical equation without changing substances?
Adjust coefficients before formulas
Remove extra atoms from products
Add catalysts to the reactants
Alter subscripts inside formulas
If a reaction starts with four hydrogen atoms and two oxygen atoms, which product set preserves mass?
Two H2O molecules total
Four H2O molecules total
Three H2O molecules total
One H2O molecule total
Why does balancing equations not require changing chemical formulas?
Formulas show fixed atom ratios
Formulas are only for gases
Formulas are optional labels
Formulas control reaction speed
In the bottom diagram, more hydrogen molecules are shown than oxygen. What is the balanced product outcome?
One water molecule forms
Two water molecules form
Three water molecules form
Four water molecules form
Which substances are on the reactant side when forming carbon dioxide in the diagram?
Carbon dioxide and oxygen atoms
Carbon and oxygen gas molecules
Carbon atoms and water molecules
Carbon dioxide and hydrogen gas
How many oxygen atoms are shown combining with one carbon atom to form carbon dioxide?
Four oxygen atoms
Three oxygen atoms
One oxygen atom
Two oxygen atoms
What does the balanced scale image suggest about reactants and products?
Reactants always weigh more
They have equal total mass only
Products always weigh more
They have equal total atoms
In the model, what is the product formed from carbon and oxygen gas?
Carbon monoxide (CO)
Water (H2O)
Carbon dioxide (CO2)
Ozone (O3)
Which statement best describes a balanced chemical equation for this reaction?
Only oxygen atoms are conserved
Atoms change into different elements
Molecules are created from nothing
Atoms of each element are conserved
If the reactants have one carbon atom and two oxygen atoms, how many of each must the product show when balanced?
One carbon, one oxygen
One carbon, two oxygens
Two carbon, two oxygens
Two carbon, one oxygen
Which equation matches the particle diagram for forming carbon dioxide?
C + O → CO2
C + O2 → CO2
C + O3 → CO2
CO + O → CO2
Why is O2 used as a reactant rather than single O atoms in the diagram?
Oxygen commonly exists as diatomic molecules
Single oxygen atoms are heavier
Diatomic oxygen cannot react with carbon
Oxygen atoms only exist in solids
Which count confirms the product is carbon dioxide in the particle model?
Two carbons with two oxygens
One carbon with three oxygens
Two carbons with one oxygen
One carbon with two oxygens
What must be true for the chemical equation to be balanced, as shown by the scale?
Same number of each atom on both sides
Same number of molecules on both sides
More atoms on the product side
Fewer atoms on the reactant side
Which statement best describes a coefficient in a chemical equation?
A number placed before a formula
A symbol written after a formula
A letter replacing an element name
A sign showing the reaction arrow
When balancing an equation, what are you allowed to change?
Only the coefficients before formulas
The chemical formulas of reactants
The element symbols in products
The subscripts inside each formula
What role does a coefficient play in a chemical equation?
It acts as a multiplier of atoms
It adds new reactant substances
It changes the element types
It reduces reaction temperature
In the example with H2 and O2 forming H2O, what must be balanced on both sides?
The total number of atoms
The length of each formula
The size of molecule drawings
The position of the arrow symbol
Why is placing coefficients in front of formulas useful when balancing?
It changes atom totals without altering formulas
It replaces elements with new ones
It switches products back to reactants
It removes oxygen from reactants
Which choice shows the correct placement of a coefficient?
H2^2 means squared hydrogen
H2=2 means equation equals two
H22 means twenty-two H atoms
2H2 means two H2 molecules
A scale labeled “Unbalanced” shows reactants and products uneven. What does this represent?
Mass units are changed to grams
Molecules have different shapes
Atom counts are not equal yet
Temperatures differ on both sides
Which step would help balance H2 + O2 → H2O?
Change O2 to O
Rewrite arrow as an equal sign
Add a coefficient to H2O
Remove the subscript in H2
What does the red word “formula” emphasize in the notes?
Formulas are written only for products
Formulas cannot be changed while balancing
Formulas must be replaced by symbols
Formulas should always be longest
Which description matches the definition of coefficient from the notes?
A number in front of a symbol or formula
A letter naming an element or compound
A sign that separates reactants and products
A diagram showing reactant particle counts
