Matter Interactions Unit Test
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Question
Cobalt has a mass number of 59 and an atomic number of 27. A student wants to create a model of a cobalt atom. Which statement about the model is correct?(1 point)
Responses
The model should show 27 protons and 32 neutrons.
The model should show 27 protons and 32 neutrons.
The model should show 32 protons and 59 neutrons.
The model should show 32 protons and 59 neutrons.
The model should show 59 protons and 27 neutrons.
The model should show 59 protons and 27 neutrons.
The model should show 27 protons and 27 neutrons.
The model should show 27 protons and 27 neutrons.
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The correct statement about the model of a cobalt atom is: The model should show 27 protons and 32 neutrons.
Question
In a molecule of lithium sulfide, there are two atoms of lithium and one atom of sulfur. Which statement about lithium sulfide is correct?(1 point)
Responses
The chemical formula for lithium sulfide is LiS2.
The chemical formula for lithium sulfide is LiS 2 .
Both lithium and sulfur form positive ions.
Both lithium and sulfur form positive ions.
The atoms in lithium sulfide are held together by bonds.
The atoms in lithium sulfide are held together by bonds.
A molecular model of lithium sulfide would have two spheres.
The correct statement about lithium sulfide is: The atoms in lithium sulfide are held together by bonds.
Matter Interactions Unit Test
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Question
Use the periodic table to answer the question.
An illustration shows the periodic table.
Which element has the same number of valence electrons as bromine (Br)?
(1 point)
Responses
chlorine (Cl)
chlorine (Cl)
krypton (Kr)
krypton (Kr)
selenium (Se)
selenium (Se)
potassium (K)
potassium (K)
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The element that has the same number of valence electrons as bromine (Br) is chlorine (Cl).
Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
Responses
They are both colorless.
They are both colorless.
They are both hard and brittle.
They are both hard and brittle.
They have similar reactivity.
They have similar reactivity.
They have similar atomic weights.
The reason why sodium (Na) and potassium (K) are in the same group on the periodic table is because they have similar reactivity.
A student cuts some fabric into two pieces. Is this change physical or chemical?(1 point)
Responses
It is a chemical change because the size changes.
It is a chemical change because the size changes.
It is a physical change because the process is reversible.
It is a physical change because the process is reversible.
It is a physical change because there is no reaction.
It is a physical change because there is no reaction.
It is a chemical change because there is no phase change.
It is a chemical change because there is no phase change.
Cutting fabric into two pieces is a physical change because it is reversible and there is no reaction taking place.
How are chemical changes different from physical changes?(1 point)
Responses
They involve heat.
They involve heat.
They include shifts in the phase of matter.
They include shifts in the phase of matter.
They form new substances.
They form new substances.
They are reversible.
Chemical changes are different from physical changes because they form new substances.
How does a balanced chemical equation demonstrate the Law of Conservation of Mass?(1 point)
Responses
it shows that all compounds remain bonded after the reaction
it shows that all compounds remain bonded after the reaction
it shows that the properties of the elements stay the same after the reaction
it shows that the properties of the elements stay the same after the reaction
it shows that no atoms have been gained or lost during the reaction
it shows that no atoms have been gained or lost during the reaction
it shows that only physical changes follow the Law of Conservation of Mass
A balanced chemical equation demonstrates the Law of Conservation of Mass by showing that no atoms have been gained or lost during the reaction.
Matter Interactions Unit Test
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Question
Sodium reacts with chlorine to form the compound sodium chloride, or salt. The chemical formula below shows how the two elements combine into a compound.
2Na + Cl2 → 2NaCl
If the total mass of the reactants is 58.44 amu, what will be the total mass of the products?
(1 point)
Responses
116.88 amu
116.88 amu
60 amu
60 amu
58.44 amu
58.44 amu
29.22 amu
29.22 amu
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The total mass of the products can be determined by multiplying the total mass of the reactants by the stoichiometric ratio (coefficient ratio) of the products to the reactants. In this case, since the ratio of NaCl to Na is 2:2 and the ratio of NaCl to Cl2 is also 2:1, the total mass of the products will be the same as the total mass of the reactants, which is 58.44 amu.
Therefore, the correct answer is: 58.44 amu.
Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
Responses
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.
Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
The procedure that could be used to demonstrate that matter is conserved during a physical change is: Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Matter Interactions Unit Test
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Question
One molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine in a reaction. How many atoms are in the products?(1 point)
Responses
two
two
six
six
three
three
four
four
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In the reaction of one molecule of bromine (Br2) and two molecules of potassium chloride (KCl), the products are potassium bromide (KBr) and chlorine gas (Cl2).
The products consist of one molecule of KBr and one molecule of Cl2.
Therefore, the total number of atoms in the products is:
2 (atoms in KBr) + 2 (atoms in Cl2) = 4 atoms.
Thus, the correct answer is: four.