AnswersCR03101 ChemistryUnit Test

Unit Test — Unit test Answers

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A year has 365 days, and a day has 24 hours. If an hour has 60 minutes and a minute has 60 seconds, how many seconds are there in 1 year?

A
54,750 s
B
525,600 s
C
3.15 107 s
Option C
D
1.89 109 s
Option D
2
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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
3

What is the molar mass of fluorine, F2?

A
9.00 g/mol
B
18.00 g/mol
C
19.00 g/mol
D
38.00 g/mol
4

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
5

A teacher wants to figure out the amount of a solution that is needed for a titration experiment in a class lab. The class has 15 students, and each experiment needs 50 mL of solution. If each student will perform the experiment two times, how many mL of solution will the teacher need for the whole class?

A
375 mL
B
750 mL
C
1500 mL
D
3000 mL
6

Avogadro’s number was calculated by determining the number of atoms in

A
12.00 g of carbon-12.
B
14.00 g of carbon-12.
C
12.00 g of oxygen.
D
14.00 g of oxygen.
7

How would you write 16,340 in scientific notation with 2 significant figures?

A
16,300
B
1.63 x 104
C
16,000
D
1.6 x 104
8

Zachary adds 26.64 g to 12.557 g. How many significant figures should his answer have?

A
two
B
three
C
four
D
five
9

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
10

Which expression is equal to the number of grams (g) in 2.43 kilograms (kg)?

A
2.43 kilograms times StartFraction 1000 grams over 1 kilogram EndFraction.
Option A
B
2.43 grams times StartFraction 1 kilogram over 1000 grams EndFraction.
Option B
C
StartFraction 1 over 2.43 kilograms EndFraction times StartFraction 1000 grams over 1 kilogram EndFraction.
Option C
D
StartFraction 1 over 2.43 kilograms EndFraction times StartFraction 1 kilogram over 1000 grams EndFraction.
Option D
11

The hydrogen ion concentration of a vinegar solution is 0.00010 M. How is this concentration written in scientific notation?

A
1.0 10–5 M
Option A
B
1.0 10–4 M
Option B
C
1.0 104 M
Option C
D
1.0 105 M
Option D
12

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
13

The volume of a sample of water is 2.5 milliliters (mL). The volume of this sample in liters (L) is

A
2.5 10–3 L.
Option A
B
2.5 10–2 L.
Option B
C
2.5 102 L.
Option C
D
2.5 103 L.
Option D
14

Which must be the same when comparing 1 mol of oxygen gas, O2, with 1 mol of carbon monoxide gas, CO?

A
the mass
B
the volume
C
the number of molecules
D
the number of oxygen atoms
15

Which statement best describes a mole?

A
It is used mainly for writing chemical formulas.
B
It is used for chemical equations that have reversible reactions.
C
It is used for directly comparing the amounts of substances.
D
It is used mainly for dealing with fluid substances.
16

The mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 1023. Which is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures?

Question illustration
A
1.99 10–23 g
Option A
B
1.994 10–23 g
Option B
C
2 10–23 g
Option C
D
2.0 10–23 g
Option D
17

Which is the molar mass of H2O?

A
10.02 g/mol
B
16.00 g/mol
C
17.01 g/mol
D
18.02 g/mol
18

Consider the balanced equation below.4NH3 + 3O2 2N2 + 6H2O What is the mole ratio of NH3 to N2?

Question illustration
A
2:4
B
4:2
C
4:4
D
7:2
19

The O–O bond length in oxygen gas is 1.20741 10–10 m. The atomic radius is exactly of the O–O bond length. Which is the atomic radius of oxygen, correctly written in scientific notation with the correct number of significant figures?

Question illustration
A
6 10–11
Option A
B
6.037 10–11
Option B
C
6.03705 10–11
Option C
D
6.04 10–11
Option D
20

Consider the equation below.N2 + 3H2 2NH3What is the mole ratio of hydrogen to ammonia?

Question illustration
A
1:1
B
1:2
C
3:2
D
5:4

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Unit Test — Unit test Answers — CR03101 Chemistry