AnswersCR SS Chemistry S2 201819 2026Unit Test

Unit Test — Unit test Answers

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1
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Which statement defines enzymatic activity?

A
Enzymes are required to slow down biological reactions within cells.
B
Specific enzymes can catalyze a wide variety of chemical reactions.
C
Enzymes regulate cellular functions through feedback mechanisms.
D
Enzymes bind substrates so that reactive groups have many different orientations.
2
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Consider the reaction.When does the given chemical system reach dynamic equilibrium?

Question illustration
A
when the forward and reverse reactions stop
B
when the rate of the forward reaction is higher than the rate of the reverse reaction
C
when the concentration of the reactants is higher than the concentration of the products
D
when the rates of the forward and reverse reactions are equal
3

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.
4

Combustion of gasoline in automobiles produces poisonous gases. Catalytic converters that contain solid platinum, palladium, and rhodium change these poisonous gases into harmless gases. Which statement describes the catalyst?

A
It is a homogeneous catalyst.
B
It provides an alternative pathway for the reaction.
C
It combines with poisonous gases to make them harmless.
D
It increases the energy that is needed for the reaction to occur.
5

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.
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

Which energy graph represents the nonspontaneous transition of graphite into diamond?

A
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts low on the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down a short distance, and levels out.
Option A
B
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down sharply, and levels out below the initial starting point.
Option B
C
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a small amount, then curves down to level out below the initial starting point.
Option C
D
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a moderate amount, then curves down sharply to level out below the initial starting point.
Option D
8

Which type of reaction is represented by the generic equation AB + CD AD + CB?

Question illustration
A
combustion
B
decomposition
C
single replacement
D
double replacement
9

Which of the following is not an oxidation-reduction reaction?

A
XeF6(s) XeF4(s) + F2(g)
Option A
B
2Cs(s) + I2(g) 2CsI(s)
Option B
C
2H2SO4(aq) + 2Ba(OH)2(aq) 2BaSO4(s) + 4H2O(l)
Option C
D
Zn(s) + 2AgNO3(aq) Zn(NO3)2(aq) + Ag(s)
Option D
10

What happens as the activation energy increases?

A
The pressure of the system decreases.
B
The kinetic energy of colliding molecules changes.
C
The reactant surface area decreases.
D
The reaction begins to slow down.
11

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.
12

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
13

The equation shows lead reacting with sulfuric acid to produce lead sulfate and hydrogen gas.Which type of chemical reaction does this equation represent?

Question illustration
A
synthesis
B
decomposition
C
single replacement
D
double replacement
14

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
15

Which will not appear in the equilibrium constant expression for the reaction below?

Question illustration
A
[H2O]
B
[C]
C
[H2]
D
[CO]
16

Which answer best describes what is happening in the following redox reaction?4Fe + 3O2 2Fe2O3

Question illustration
A
This is combustion.
B
This is neutralization.
C
Iron is oxidized to form rust.
D
Oxygen is oxidized to form rust.
17

Consider the following reversible reaction.What is the equilibrium constant expression for the given system?

Question illustration
A
K e q equals StartFraction StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket superscript 2 over StartBracket upper C upper H subscript 3 upper O upper H EndBracket EndFraction.
Option A
B
K e q equals StartFraction StartBracket upper C upper H subscript 3 upper H upper O EndBracket over StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket superscript 2 EndFraction.
Option B
C
K e q equals StartFraction StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket over StartBracket upper C upper H subscript 3 upper O upper H EndBracket EndFraction.
Option C
D
K e q equals sart fraction StartBracket upper C upper H subscript 3 upper O StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket EndFraction.
Option D
18

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
19

Which statement best applies collision theory to preventing a dangerous reaction from occurring?

A
Store the reactants together at a low pressure.
B
Keep all sparks or flames away from the reactants.
C
Store the reactants together at a low temperature.
D
Keep the reactants in separate containers.
20

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

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