AnswersPBCSD_Grade_Forgiveness_2003310_Physical Science_S1_2022Changes of State

Changes of State — Unit test Answers

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Which is a characteristic of all ions?

A
They are metals.
B
They have a charge.
C
They are made of two or more types of atoms.
D
They form chemical bonds through electron sharing.
2
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Shameeka is studying for an exam. She took the notes below about calcium and chlorine, which are known to form ionic bonds.Calcium, which is a metal, donates 2 electrons to chlorine.The individual calcium atoms become ions with a negative 2 charge. The bond between calcium and chlorine makes the atoms stable. Calcium and chlorine attract each other. Which best describes Shameeka’s error?

A
Calcium is a metal, so it donates protons, not electrons.
B
The individual calcium atom has a positive, not negative, 2 charge.
C
The bond formed makes the atoms unstable, not stable.
D
Calcium and chlorine repel, not attract, each other.
3

The Statue of Liberty is made out of copper and was once shiny and copper-colored. Over the years, the copper has gone through a process called oxidation, where it has changed into a new material.

A
an endothermic reaction
B
an energy formation
C
a chemical reaction
D
a precipitate formation
4

There are several different models that represent compounds. One type of model is shown.

Question illustration
A
a structural formula
B
a chemical formula
C
a space-filling model
D
a ball-and-stick model
5

How many atoms of each element are in the chemical formula Ca(OH)2?

A
1 calcium, 1 oxygen, and 1 hydrogen
B
1 calcium, 2 oxygen, and 2 hydrogen
C
2 calcium, 1 oxygen, and 2 hydrogen
D
2 calcium, 2 oxygen, and 2 hydrogen
6

Hydrochloric acid and sodium hydroxide can be combined to form sodium chloride and water. Which best explains the reaction?

A
The mass of sodium hydroxide will result in the same mass of sodium chloride.
B
The total mass of hydrochloric acid and sodium hydroxide will result in a lower total mass of sodium chloride and water.
C
The mass of hydrochloric acid will result in the same mass of sodium chloride.
D
The total mass of hydrochloric acid and sodium hydroxide will result in the same total mass of sodium chloride and water.
7

Which describes the substances that form covalent bonds?

A
a metal and a metalloid
B
a metal and a nonmetal
C
two nonmetals
D
two metals
8

Chemical A and Chemical B react in an exothermic reaction. What can be known about what will happen when Chemical A and Chemical B are mixed together?

A
The old substance will need more energy to break its chemical bonds than the new substance will release.
B
More energy will be released from the old substance than the new substance will release to form its chemical bonds.
C
The color will change as a result of the reaction.
D
The substance will bubble as a result of the reaction.
9

Lexi is balancing equations. She is finding one equation to be very difficult to balance. Which explains how to balance the equation ZnSO4 + Li2CO3 → ZnCO3 + Li2SO4?

A
One reactant and one product needs the coefficient 2.
B
The products both need a 3 coefficient.
C
The reactants both need a 2 coefficient.
D
Atoms in the equation are already in balance.
10

Which is most likely a covalent compound?

A
LiF
B
MgS
C
NH3
D
CaCl2
11

What best explains whether bromine (Br) or neon (Ne) is more likely to form a covalent bond?

Question illustration
A
Bromine forms covalent bonds because it has seven valence electrons, but neon has eight valence electrons and already fulfills the octet rule.
B
Bromine forms covalent bonds because it has many electron shells, but neon has only two electron shells and is tightly bound to its electrons.
C
Neon forms covalent bonds because it can share its valence electrons, but bromine has seven valence electrons and can gain only one more electron.
D
Neon forms covalent bonds because it has only two electron shells, but bromine has many electron shells and will lose electrons in order to fulfill the octet rule.
12

Calcium carbonate (CaCO3) is a white solid with no odor. When CaCO3 is heated, the resulting substances are calcium oxide (CaO) and carbon dioxide (CO2). CaO is a white to gray solid with no odor, and CO2 is a gas with no odor and color.Which statement describes CaCO3?

A
It is a diatomic molecule that can’t be broken down by physical means.
B
It is a diatomic molecule that can’t be broken down by chemical means.
C
It is a compound that can be broken down by physical means.
D
It is a compound that can be broken down by chemical means.
13

To what extent do covalent compounds conduct electricity?

A
always
B
usually
C
rarely
D
never
14

"Na2SO3” represents sodium sulfite.What does the 4 mean in the formula 4Na2SO3?

A
There are four atoms of sodium.
B
There are four atoms of sodium sulfite.
C
There are four molecules of sodium sulfite.
D
There are four elements in sodium sulfite.
15

The table describes the properties of four compounds.Which compounds are most likely ionic?

Question illustration
A
compounds A and B
B
compounds B and C
C
compounds C and D
D
compounds D and A
16

Harvey mixes two liquids. Which observation of the new mixture most likely indicates a precipitate is forming?

A
a cloudy appearance
B
a bubble formation
C
a change in color
D
a change in odor
17

Which best describes a chemical reaction?

A
the rearrangement of atoms by breaking and reforming chemical bonds
B
a reaction that absorbs heat from the surroundings
C
a reaction that releases heat to the surroundings
D
the rearrangement of molecules based on temperature and pressure
18

Which ionic compound is used as a building material?

A
salt
B
limestone
C
magnesium oxide
D
iron oxide
19

Which condition must be met in order for an equation to be balanced?

A
The elements in the reactants are the same as the elements in the products.
B
There are fewer elements in the reactants than there are in the products.
C
The number of atoms in the reactants is greater than the number of atoms in the products.
D
The number of atoms in the reactants equals the number of atoms in the products.
20

Which balances the equation Mg + O2 → MgO?

A
Mg + 2O2 → 4MgO
B
2Mg + 2O2 → 2MgO
C
2Mg + O2 → 2MgO
D
2Mg + 2O2 → 4MgO

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