AnswersEA ACADEMY PHYSICAL SCIENCE SPRINGUnit Test

Unit Test — Cumulative exam Answers

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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.
2
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What are the products of the combustion of a hydrocarbon?

A
carbon and oxygen
B
carbon dioxide and water
C
carbon and hydrogen
D
carbon dioxide and hydrogen
3

Which balances the equation Mg + O2 → MgO?

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

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.
5

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
6

Which clue can be used to identify a chemical reaction as a decomposition reaction?

A
The reaction involves oxygen.
B
The reaction involves ions.
C
The reaction has a single reactant.
D
The reaction has a single product.
7

Consider the balanced equation below. 2H2S + 3O2 2SO2 + 2H2OWhich option gives the correct mole ratios?

Question illustration
A
H2S:SO2 = 2:2 and O2:H2O = 3:2
B
H2S:SO2 = 2:3 and O2:H2O = 3:2
C
H2S:SO2 = 4:4 and O2:H2O = 5:4
D
H2S:SO2 = 4:6 and O2:H2O = 4:4
8

The following balanced equation shows the formation of ammonia.N2 + 3H2 2NH3How many moles of nitrogen are needed to completely convert 6.34 mol of hydrogen?

Question illustration
A
1.02 mol
B
2.11 mol
C
12.68 mol
D
19.02 mol
9

The equation below shows lithium reacting with nitrogen to produce lithium nitride.6Li + N2 2Li3NIf 12 mol of lithium were reacted with excess nitrogen gas, how many moles of lithium nitride would be produced?

Question illustration
A
4.0 mol
B
6.0 mol
C
12 mol
D
36 mol
10

Which type of reaction has the general formula of AB + CD → AD + CB?

A
synthesis
B
decomposition
C
oxidation
D
replacement
11

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.
12

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.
13

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
14

The balanced equation below shows the products that are formed when pentane (C5H12) is combusted. C5H12 + 8O2 5CO2 + 6H2OWhat is the mole ratio of oxygen to pentane?

Question illustration
A
1:6
B
6:8
C
8:1
D
5:8
15

What else is produced during the replacement reaction of silver nitrate and potassium sulfate?2AgNO3 + K2SO4 Ag2SO4 + ________

Question illustration
A
KNO3
B
2KNO3
C
K2
D
2AgNO3
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 is evidence that a chemical reaction has likely occurred?

A
a liquid slowly losing volume
B
the formation of a precipitate
C
boiling water releasing steam
D
a change in the shape of a solid
18

Which clue can be used to identify a chemical reaction as a combustion reaction?

A
Oxygen is a product.
B
A hydrocarbon reacts with oxygen.
C
Water and carbon dioxide react.
D
The reaction involves ions.
19

For a science project, Janet performs four experiments that are supposed to show a chemical reaction. She displays her results in a table.

Question illustration
A
Experiment 1
B
Experiment 2
C
Experiment 3
D
Experiment 4
20

Which is an example of a chemical reaction?

A
paper folded into tiny pieces
B
paper burned and turned into smoke
C
paper soaked in water
D
paper shredded and turned into pulp

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