AnswersIA-Chemistry A Survey of Chemistry AUnit Test

Unit Test — Unit test Answers

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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
2
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Which will not appear in the equilibrium constant expression for the reaction below?

Question illustration
A
[H2O]
B
[C]
C
[H2]
D
[CO]
3

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
4

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
5

Which represents the empirical formula for X4Y8?

A
XY2
B
X2Y4
C
X4Y8
D
XY
6

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.
7

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
8

Which shows the correct relationship between the molecular formula and the empirical formula for C2H10N2?

A
molecular formula = 2 empirical formula
Option A
B
empirical formula = 2 molecular formula
Option B
C
molecular formula = 62.1 empirical formula
Option C
D
empirical formula = 14 molecular formula
Option D
9

Consider the following equation in chemical equilibrium. C2H4(g) + H2(g) C2H6(g) + 137 kJ What happens to the amount of ethane (C2H6) when the temperature of the system is increased?

Question illustration
A
The amount of ethane decreases.
B
The amount of ethane increases initially and then decreases.
C
The amount of ethane increases.
D
The amount of ethane decreases initially and then increases.
10

Consider the chemical equilibrium of a soap that is present in its aqueous solution. C17H35COONa(aq) C17H35COO–(aq) + Na+(aq)sodium stearate (soap) stearate ion What will happen if a large quantity of NaCl is added to the aqueous solution?

Question illustration
A
The equilibrium will shift to the right, favoring the dissociation of soap in aqueous solution.
B
The equilibrium will shift to the left to such an extent that it leads to the precipitation of solid soap.
C
The equilibrium will not be affected by the addition of NaCl to the solution.
D
The equilibrium will be permanently destroyed by the addition of NaCl.
11

Which reaction will most likely take place based on the activity series?Li > K > Ba > Ca > Na > Mn > Zn > Cr > Fe > Cd > Ni > H > Sb > Cu > Ag > Pd > Hg > Pt

A
Pt + FeCl3
Option A
B
Mn + CaO
Option B
C
Li + ZnCO3
Option C
D
Cu + 2KNO3
Option D
12

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
13

The dissociation of a weak electrolyte is suppressed when

A
a strong electrolyte with a common ion is added to the weak electrolyte solution.
B
a strong salt is dissolved with the weak electrolyte solution.
C
a strong electrolyte with a different ion than the weak electrolyte is added.
D
the strong electrolyte solidifies in the presence of the weak electrolyte.
14

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.
15

What is the percent by mass of oxygen in carbon dioxide (CO2)?Use .

Question illustration
A
27.29%
B
57.12%
C
72.71%
D
79.99%
16

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
17

According to Le Chatelier’s principle, what happens when the concentration of reactants is doubled in a chemical reaction that was in equilibrium?

A
The equilibrium shifts to the right to favor the formation of products.
B
The equilibrium shifts to the left to favor the formation of reactants.
C
The equilibrium is unaffected by the increase in concentration.
D
The equilibrium is lost because the concentrations have been disturbed.
18

Consider the equation below.What is the equilibrium constant expression for the given reaction?

Question illustration
A
K subscript e q equals StartFraction bracket upper C a upper O EndBracket over upper C a upper C upper O subscript 3 EndBracket EndFraction.
Option A
B
K subscript e q equals StartFraction StartBracket upper C upper O subscript 2 EndBracket StartBracket upper C a upper O EndBracket over StartBracket upper C a upper C upper O subscript 3 EndBracket EndFraction.
Option B
C
K subscript e q equals StartBracket upper C upper O subscript 2 EndBracket.
Option C
D
K subscript e q equals StartFraction 1 over StartBracket upper C upper O subscript 2 EndBracket EndFraction.
Option D
19

What is the percent by mass of potassium in K3Fe(CN)6?Use .

Question illustration
A
16.96%
B
21.88%
C
25.53%
D
35.62%
20

A reaction occurs when solid X is placed into solution Y. As a result, the temperature of the new solution increases by 3°C. The temperature rises another 2°C when more of solid X is added to the solution. What does this indicate about the effect of adding more solid?

A
It increased the number of molecular collisions.
B
It decreased the number of molecular collisions.
C
It decreased the space between the molecules and lowered the reaction rate.
D
It increased the space between the molecules and increased the reaction rate.

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