WorksheetsUnit 4 Chemistry 7th Grade Pre-Test
Total questions: 20
Worksheet time: 20mins
Evidence of a chemical reaction is anything that shows
a new substance has formed
a solid dissolved in a liquid
interaction between 2 gases
a change in the state of matter
One of the signs of a chemical reaction taking place is:
Bubbles are produced
Reactants are not combining
Products are not forming
Color is not changing
Which of the following describes a precipitate?
a liquid forms when a block of metal is heated
a solid forms when one liquid is poured into another
a gas forms when a solid is placed in a liquid
bubbles form when an acid is poured on a rock
Which is NOT an indication of a chemical change?
temperature change
formation of a precipitate
shape change
production of light
You know you a chemical reaction has occurred if
there is a precipitate.
there is a color change.
there is a temperature change.
All of these answers are evidence.
Which of the following is an example that includes evidence of a chemical reaction?
A sample of zinc is placed in water and it settles to the bottom
A solid block of ice is heated and it completely melts into a liquid.
Sugar that is burned gives off an odor and turns brown and then black.
A tomato is placed into a blender and chopped up into smaller pieces.
A student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles -
could show that a gas is forming.
always rise to the top of a liquid.
are almost always perfectly spherical.
usually burst after a few minutes.
Jonathan places a pot of water on a stove. As the water boils, how does the state of the water change?
from gas to liquid
from liquid to gas
from liquid to solid
from solid to liquid
Matter changes state when...
energy is added or removed
energy is added
energy is removed
there is no energy
What state of matter is present at 50° C for water?
solid
liquid
gas
plasma
The particles in water move fastest in water that is _______________.
boiling
frozen
liquid
melting
If a substance is heated, what happens to its molecules?
they slow down and move closer together
the speed up and move closer together
they slow down and move farther apart
they speed up and move farther apart
When thermal energy is decreased in a liquid, what change in state is happening?
Melting
Freezing
Condensation
Evaporation
When thermal energy is increased in a solid, what change in state is happening?
Melting
Evaporation
Freezing
Condensation
What is the chemical formula for the molecule shown here?
NH
HN3
NH3
N3H3
Which state of matter would a bulk substance with this composition probably be found in?
solid
liquid
gas
plasma
In this model, each ball represents an atom. How many atoms make up one of these molecules?
3
6
10
1
H2O is most accurately described as a ___________________.
molecule
compound
element
atom
Molecules and compounds are created when multiple atoms bond together, but how are they different?
Compounds have to have atoms from different elements bonded together
Molecules have to have atoms from different elements bonded together
They are the same and there is no difference
Molecules are building blocks of compounds
What purpose do molecular models, drawings, and diagrams serve? (check all that apply)
They allow us visual representations for things we can't normally see
They make concepts more difficult to understand.
They serve no purpose.
They are fun to build.
