Atoms, Molecules,
Pure Substances, & Mixtures
CRCT Prep
Part I
A scientist combines oxygen and hydrogen to
form water. This combination illustrates that
water is
A. an atom.
B. an element.
C. a mixture.
D. a compound.
Copper is an element that is used in electrical
wires. What is the smallest unit of copper that still
maintains the characteristics of copper?
A. the atom
B. the electron
C. the nucleus
D. the proton
What is the smallest particle of the element gold
(Au) that can still be classified as gold?
A. atom
B. molecule
C. neutron
D. proton
Which of the following illustrations represents a
pure substance?
A.
B.
C.
D.
Which formulas represent compounds?
A. O2, H2O2
B. CO2, H2O
C. H2, CO2
D. H2, O2
If different kinds of atoms are represented by
different colored dots, which picture represents a
sample of a compound?
A.
C.
B.
D.
If different kinds of atoms are represented by
different colored dots, which picture below
represents a mixture?
A.
B.
C.
D.
Which of the following is a compound?
A. oxygen
B. water
C. nitrogen
D. air
A mixture of powdered iron and sulfur reacts
chemically when heated. What will be formed?
A. a single element
B. two other elements
C. a solution
D. a compound
A solution in a dish contains 3.0 grams of salt
dissolved in 100 grams of water. If 50 grams of
the water evaporate, the solution is
A. a compound.
B. a mixture.
C. an element.
D. a solid.
Carbon dioxide is
A. an element.
B. a compound.
C. a solution.
D. a mixture.
A chemical change combining two elements
results in
A. an atom.
B. a compound.
C. an element.
D. a mixture.
Atoms, Molecules,
Pure Substances, & Mixtures
CRCT Prep
Part II
John has a mixture of salt, sand, and iron filings. To remove
the iron filings from the mixture, John should
A. run a magnet through the mixture.
B. put the mixture in water and stir it.
C. throw the mixture into the air and see which
material fall first.
D. blow on it and keep what does not blow away.
Which of the following elements is part of the
chemical formula for table salt?
A. Na
B. Si
C. S
D. O
When mud and water are combined, the result is
A. a mixture.
B. a compound.
C. an element.
D. a molecule.
Which symbolizes a molecule of a compound?
A. He
B. Be
C. N2
D. NaCl
Which of the following is an element?
A. air
B. salt
C. water
D. oxygen
Putting sand and salt together makes
A. a compound.
B. an element.
C. a mixture.
D. a solution.
Plastic, wood, and iron are all made up of
A. cells.
B. atoms.
C. carbon.
D. plants.
Water is
A. a compound.
B. an element.
C. a solution.
D. a mixture.
An atom is to an element, as a molecule is to a
A. metal.
B. nonmetal.
C. metalloid.
D. compound.
All of the substances on the periodic table are
classified as elements because they
A. are pure substances.
B. are composed of atoms.
C. cannot be broken down into
other substances.
D. cannot be dissolved in water or
other
liquids.
Salt (NaCl) is a common substance. Salt is which
of the following?
A. atom
B. element
C. compound
D. mixture
Atoms, Molecules,
Pure Substances, & Mixtures
CRCT Prep
Part III
Oxygen and hydrogen atoms combine to form water.
When one oxygen and two hydrogen atoms combine, what
forms?
A. a different atom
B. a different element
C. a molecule
D. a neutron
The smallest part of matter that is identifiable
as an element is the
A. atom.
B. molecule.
C. cell.
D. compound.
Several centuries ago, men called alchemists tried to
transform common metals into gold. Even though they tried
many different chemical and physical methods, they never
succeeded because
A. they could not heat common metals to
extremely high temperatures.
B. the common metals they worked with
were not pure.
C. they did not add the correct material to
the common metal.
D. elements cannot be changed to other
elements by physical or chemical means.
Which picture illustrates the structure of a
molecule of water?
A.
C.
B.
D.
Which of the following is best classified as a
mixture?
A. carbon dioxide
B. water
C. soil
D. iron
A substance made up of two or more elements
that have been chemically combined is called
A. an atom.
B. a compound.
C. an element.
D. a mixture.
Because zinc can combine with other
substances but cannot be changed into a
simpler substance by an ordinary chemical
process, zinc is classified as
A. a compound.
B. a mixture.
C. an element.
D. an acid.
In the chemical formula for ammonia, NH3, what does
the subscript 3 represent?
A. The number of nitrogen and hydrogen
in each molecule of ammonia.
B. The number of hydrogen atoms in each
molecule of ammonia.
C. The number of ammonia molecules that
bond together.
D. The number of nitrogen atoms in each
molecule of ammonia.
atoms
will
A mixture of iron filings and sulfur can easily
be separated by
A. placing the mixture in water.
B. performing a chemical reaction.
C. heating the mixture.
D. using a magnet.