Q. How many atoms are in 2 moles of oxygen gas (O2)?
A.
6.022 x 10^23
B.
1.2044 x 10^24
C.
3.011 x 10^23
D.
12.044 x 10^23
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Solution
Each O2 molecule has 2 oxygen atoms. Number of atoms = moles x Avogadro's number x 2 = 2 moles x 6.022 x 10^23 molecules/mole x 2 = 1.2044 x 10^24 atoms.
Correct Answer: B — 1.2044 x 10^24
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Q. How many grams are in 0.25 moles of glucose (C6H12O6)?
A.
30 g
B.
45 g
C.
75 g
D.
90 g
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Solution
Molar mass of C6H12O6 = 6*12 + 12*1 + 6*16 = 180 g/mol. Mass = 0.25 moles x 180 g/mol = 45 g.
Correct Answer: D — 90 g
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Q. How many grams are in 0.25 moles of KCl?
A.
35 g
B.
70 g
C.
17.5 g
D.
140 g
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Solution
Molar mass of KCl = 39 + 35.5 = 74.5 g/mol. Mass = moles x molar mass = 0.25 moles x 74.5 g/mol = 18.625 g.
Correct Answer: B — 70 g
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Q. How many grams are in 0.25 moles of sulfuric acid (H2SO4)?
A.
49 g
B.
98 g
C.
24.5 g
D.
12.25 g
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Solution
Molar mass of H2SO4 = 98 g/mol. Mass = moles x molar mass = 0.25 moles x 98 g/mol = 24.5 g.
Correct Answer: A — 49 g
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Q. How many grams are in 3 moles of glucose (C6H12O6)?
A.
180 g
B.
360 g
C.
540 g
D.
90 g
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Solution
Molar mass of glucose = 6*12 + 12*1 + 6*16 = 180 g/mol. Mass = moles x molar mass = 3 moles x 180 g/mol = 540 g.
Correct Answer: B — 360 g
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Q. How many molecules are present in 2 moles of water (H2O)?
A.
6.022 x 10^23
B.
1.2044 x 10^24
C.
3.011 x 10^23
D.
12.044 x 10^24
Show solution
Solution
Number of molecules = moles x Avogadro's number = 2 moles x 6.022 x 10^23 molecules/mole = 1.2044 x 10^24 molecules.
Correct Answer: B — 1.2044 x 10^24
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Q. How many moles are in 1.5 kg of KCl?
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Solution
Molar mass of KCl = 39 + 35.5 = 74.5 g/mol. Number of moles = mass/molar mass = 1500 g / 74.5 g/mol ≈ 20.1 moles.
Correct Answer: B — 20
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Q. How many moles are in 10 grams of NaOH?
A.
0.25
B.
0.5
C.
0.75
D.
1
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Solution
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 10 g / 40 g/mol = 0.25 moles.
Correct Answer: A — 0.25
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Q. How many moles are in 100 grams of CaCO3?
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Solution
Molar mass of CaCO3 = 40 + 12 + 3*16 = 100 g/mol. Number of moles = mass/molar mass = 100 g / 100 g/mol = 1 mole.
Correct Answer: A — 1
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Q. How many moles are in 180 grams of water?
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Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = 180 g / 18 g/mol = 10 moles.
Correct Answer: A — 1
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Q. How many moles are in 200 grams of H2O?
A.
11.11
B.
10
C.
9
D.
8.89
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Solution
Molar mass of H2O = 18 g/mol. Number of moles = mass / molar mass = 200 g / 18 g/mol = 11.11 moles.
Correct Answer: A — 11.11
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Q. How many moles are in 200 grams of H2SO4?
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Solution
Molar mass of H2SO4 = 2 + 32 + 16*4 = 98 g/mol. Number of moles = 200 g / 98 g/mol = 2.04 moles.
Correct Answer: B — 2
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Q. How many moles are in 36 grams of water (H2O)?
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Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = mass/molar mass = 36 g / 18 g/mol = 2 moles.
Correct Answer: A — 1
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Q. How many moles are in 5.6 liters of a gas at STP?
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Solution
At STP, 1 mole of gas occupies 22.4 L. Number of moles = volume / molar volume = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: C — 1
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Q. How many moles are in 5.6 liters of an ideal gas at STP?
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Solution
At STP, 1 mole of gas occupies 22.4 L. Therefore, number of moles = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: B — 0.5
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Q. How many moles are in 50 grams of CaCO3?
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Solution
Molar mass of CaCO3 = 100 g/mol. Number of moles = mass / molar mass = 50 g / 100 g/mol = 0.5 moles.
Correct Answer: B — 1
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Q. How many moles are in 50 grams of H2O?
A.
2.78
B.
1.39
C.
0.56
D.
3.06
Show solution
Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = mass/molar mass = 50 g / 18 g/mol = 2.78 moles.
Correct Answer: B — 1.39
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Q. How many moles are in 50 grams of NaOH?
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Solution
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 50 g / 40 g/mol = 1.25 moles.
Correct Answer: B — 0.5
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Q. How many moles are in 50 grams of sodium (Na)?
A.
1.08
B.
2.5
C.
0.5
D.
0.25
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Solution
Molar mass of Na = 23 g/mol. Number of moles = mass / molar mass = 50 g / 23 g/mol ≈ 2.17 moles.
Correct Answer: A — 1.08
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Q. How many moles are in 500 mL of a 2 M NaCl solution?
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Solution
Moles = molarity x volume (in L) = 2 M x 0.5 L = 1 mole.
Correct Answer: B — 1
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Q. How many moles are in 88 grams of CH4?
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Solution
Molar mass of CH4 = 12 + 4*1 = 16 g/mol. Number of moles = mass/molar mass = 88 g / 16 g/mol = 5.5 moles.
Correct Answer: B — 2
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Q. How many moles are in 88 grams of O2?
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Solution
Molar mass of O2 = 16*2 = 32 g/mol. Number of moles = mass/molar mass = 88 g / 32 g/mol = 2.75 moles.
Correct Answer: B — 2
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Q. How many moles are in 88 grams of oxygen (O2)?
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Solution
Molar mass of O2 = 32 g/mol. Number of moles = mass / molar mass = 88 g / 32 g/mol = 2.75 moles.
Correct Answer: A — 2
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Q. If 0.5 moles of a gas occupy 11.2 liters at STP, what is the molar volume of the gas?
A.
22.4 L
B.
11.2 L
C.
5.6 L
D.
44.8 L
Show solution
Solution
At STP, 1 mole of gas occupies 22.4 L. Therefore, the molar volume is 22.4 L.
Correct Answer: A — 22.4 L
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Q. If 1 mole of a gas occupies 22.4 L at STP, how many liters will 0.5 moles occupy?
A.
11.2 L
B.
22.4 L
C.
44.8 L
D.
5.6 L
Show solution
Solution
Volume = moles x volume per mole = 0.5 moles x 22.4 L/mole = 11.2 L.
Correct Answer: A — 11.2 L
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Q. If 1 mole of a gas occupies 22.4 L at STP, how much volume will 0.5 moles occupy?
A.
11.2 L
B.
22.4 L
C.
44.8 L
D.
5.6 L
Show solution
Solution
Volume = moles x volume per mole = 0.5 moles x 22.4 L/mole = 11.2 L.
Correct Answer: A — 11.2 L
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Q. If 3 moles of a gas occupy 60 liters at STP, what is the molar volume of the gas?
A.
20 L
B.
30 L
C.
40 L
D.
60 L
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Solution
Molar volume = total volume / number of moles = 60 L / 3 moles = 20 L/mole.
Correct Answer: B — 30 L
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Q. If 3 moles of a gas occupy 60 liters, what is the volume occupied by 1 mole of the gas at the same conditions?
A.
20 L
B.
30 L
C.
15 L
D.
10 L
Show solution
Solution
Volume per mole = total volume / number of moles = 60 L / 3 moles = 20 L/mole.
Correct Answer: A — 20 L
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Q. What is the mass of 0.5 moles of CaCO3?
A.
50 g
B.
25 g
C.
100 g
D.
75 g
Show solution
Solution
Molar mass of CaCO3 = 40 + 12 + 16*3 = 100 g/mol. Mass = moles x molar mass = 0.5 moles x 100 g/mol = 50 g.
Correct Answer: B — 25 g
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Q. What is the mass of 0.5 moles of NaCl?
A.
29 g
B.
58 g
C.
14 g
D.
0.5 g
Show solution
Solution
Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol. Mass = moles x molar mass = 0.5 moles x 58.5 g/mol = 29.25 g.
Correct Answer: A — 29 g
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