AnswersLA-Chemistry AUnit Test

Unit Test — Unit test Answers

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This formula equation is unbalanced.Pb(NO3)2(aq) + Li2SO4(aq) PbSO4(s) + LiNO3(aq) Which coefficient should appear in front of LiNO3 in the balanced equation?

Question illustration
A
1
B
2
C
3
D
4
2
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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.
3

Which statement describes a chemical reaction?

A
Reactants form products when atoms change state.
B
Products form reactants when atoms change state.
C
Reactants form products when atoms are rearranged.
D
Products form reactants when atoms are rearranged.
4

Which statement best characterizes chemical reactions?

A
They always occur very quickly.
B
Their rates vary significantly.
C
Their rates are always slow.
D
They rarely occur in the natural environment.
5

Which statement is true about ionic compounds?

A
Solid ionic compounds are good conductors of electricity.
B
Ionic compounds have varying solubilities in water.
C
Ionic compounds have very low melting points.
D
Ionic compounds are very easy to bend.
6

What is the word equation for atoms of magnesium reacting with molecules of oxygen to produce magnesium oxide?

A
magnesium + magnesium oxide oxygen
Option A
B
magnesium + oxygen magnesium oxide
Option B
C
magnesium oxide + oxygen magnesium
Option C
D
magnesium + oxygen magnesium + oxygen
Option D
7

The reaction below was carried out in an acidic solution.Which statement is true about this equation?

Question illustration
A
Although it is unbalanced, it can be balanced by using the half-reaction method.
B
It has been balanced by using the half-reaction method.
C
It has been balanced by directly using spectator ions.
D
Although it is unbalanced, it can be balanced by directly using spectator ions.
8

Consider the half reaction below.Which statement best describes what is taking place?

Question illustration
A
Chlorine is losing electrons and being oxidized.
B
Chlorine is losing electrons and being reduced.
C
Chlorine is gaining electrons and being oxidized.
D
Chlorine is gaining electrons and being reduced.
9

Which compound has the highest melting point?

A
Al2(CO3)3
B
C12H22O11
C
C8H18
D
H2O
10

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
11

Lewis structures cannot

A
show the number of valence electrons.
B
show the location of bonds.
C
show the strength of bonds.
D
show how many bonds are present in a molecule.
12

An element has six valence electrons available for bonding. Which group of the periodic table does this element most likely belong to?

A
group 2
B
group 4
C
group 16
D
group 18
13

Which of these scenarios is most likely a chemical reaction?

A
A gas turns into a liquid as it releases energy.
B
A liquid becomes a gas as it absorbs energy.
C
Two white solids are added to a colorless liquid, and a colorless liquid remains.
D
Two colorless liquids are added together, and a colorless liquid and a green solid remain.
14

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
15

Consider the half reactions below for a chemical reaction.What is the overall equation for this chemical reaction?

Question illustration
A
Upper Z n (s) plus upper C u superscript 2 plus (a q) right arrow upper Z n superscript 2 plus (a q) plus upper C u (s).
Option A
B
Upper Z n (s) plus upper C u superscript 2 plus (a q) right arrow upper C u superscript 2 plus (a q) plus upper Z n (s).
Option B
C
Upper Z n superscript 2 plus (a q) plus upper C u (s) right arrow upper C u superscript 2 plus (a q) plus upper Z n (s).
Option C
D
Upper Z n superscript 2 plus (a q) plus 2 e superscript minus right arrow upper C u superscript 2 plus (a q) plus 2 e superscript plus.
Option D
16

How do ionic bonds affect the properties of ionic compounds?

A
The bonds weakly hold ions together, increasing the melting point.
B
The bonds strongly hold ions together, reducing the boiling point.
C
The bonds prevent ions from moving throughout the crystal, so a solid ionic compound is a poor conductor.
D
The bonds prevent electrons from moving throughout the crystal, so a solid ionic compound is a good conductor.
17

Which symbol can be used to indicate a chemical reaction that takes place in the presence of a catalyst?

A
350 degrees Celsius over a right-pointing arrow.
Option A
B
Upper P t over a right-pointing arrow.
Option B
C
0.5 a t m over a right arrow.
Option C
D
Delta over a right arrow.
Option D
18

Consider the reaction below.What is being reduced?

Question illustration
A
only K
B
only Br2
C
both K and Br2
D
neither K nor Br2
19

Consider the chemical equation for the combustion of sugar._C6H12O6(s) + _O2(g) _CO2(g) + _H2O(l)Which sequence of coefficients should be placed in the blanks to balance this equation?

Question illustration
A
1, 6, 6, 6
B
6, 1, 6, 1
C
3, 3, 3, 6
D
1, 3, 3, 6
20

When two substances are mixed together, a color change is observed. Does this mean that a chemical reaction has definitely occurred?

A
Yes because any change indicates a chemical reaction.
B
No because some physical changes produce color changes.
C
No because color changes are not indicators of chemical reactions.
D
Yes because color changes occur only when new compounds are formed.

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