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Mole Concept & Molecular Formulas


Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 
You have 0.330 mole of each of the following elements: Be, B, Br, Ba, and Bi. Which sample has the largest mass?
a.
Be
b.
B
c.
Br
d.
Ba
e.
Bi
 

 2. 
You have 4.15 g of each of the following elements: Ca, Cu, Ce, Cs, Cf. Which sample contains the largest number of atoms?
a.
Ca
b.
Cu
c.
Ce
d.
Cs
e.
Cf
 

 3. 
Calculate the number of moles in 39 g silicon.
a.
9.1 x 10-4 mol
b.
0.72 mol
c.
1.4 mol
d.
11 mol
e.
1.1 x 103 mol
 

 4. 
What is the mass of 5.1 mol P?
a.
6.3 x 10-3 g
b.
1.6 x 10-1 g
c.
6.1 g
d.
1.6 x 102 g
e.
2.0 x 102 g
 

 5. 
A 3.6 g sample of lithium contains ____ atoms.
a.
5.2 x 10-1
b.
1.7 x 1023
c.
3.1 x 1023
d.
1.2 x 1024
e.
1.5 x 1025
 

 6. 
What is a correct method for calculating the mass of 1.9 x 1023 potassium atoms?
a.
6.02 x 1023 atoms K 115_mole-molec_form_files/i0070000.jpg
b.
1.9 x 1023 atoms K 115_mole-molec_form_files/i0070001.jpg
c.
1.9 x 1023 atoms K 115_mole-molec_form_files/i0070002.jpg
d.
1.9 x 1023 atoms K 115_mole-molec_form_files/i0070003.jpg
e.
1.9 x 1023 atoms K 115_mole-molec_form_files/i0070004.jpg
 

 7. 
What is a correct method for calculating the number of atoms in 3.5 x 10-3 mole Cr?
a.
3.5 x 10-3 mol Cr 115_mole-molec_form_files/i0080000.jpg
b.
3.5 x 10-3 mol Cr 115_mole-molec_form_files/i0080001.jpg
c.
3.5 x 10-3 mol Cr 115_mole-molec_form_files/i0080002.jpg
d.
3.5 x 10-3 mol Cr 115_mole-molec_form_files/i0080003.jpg
e.
3.5 x 10-3 mol Cr 115_mole-molec_form_files/i0080004.jpg
 

 8. 
Pennies minted after 1983 are composed of 97% zinc and 3.0% copper and have a mass of 2.46 g. How many moles of copper are in a penny?
a.
0.0012 mol
b.
0.014 mol
c.
0.038 mol
d.
0.040 mol
e.
25 mol
 

 9. 
Which of the following statements about the mole is false?
a.
One mole of an element corresonds to one Avogadro nuber of atoms.
b.
One mole of an element has a mass equal to its atomic mass expressed in grams.
c.
One mole of diatomic hydrogen gas contains two moles of hydrogen atoms.
d.
One mole of water contains 1/2 mole of oxygen atoms.
e.
none of the above
 

 10. 
How many atoms are present in  2.5 moles?
a.
6.6 x 1023 atoms
b.
6.6 x 10-25 atoms
c.
1.5 x 1024 atoms
d.
6.02 x 1023 atoms
e.
none of the above
 

 11. 
If you have 1.8 x 1024 atoms of copper, how many moles of copper do you have?
a.
0.330 mol Cu
b.
3.00 mol Cu
c.
0.750 mol Cu
d.
2.00 mol Cu
e.
none of the above
 

 12. 
How many atoms are in 5.80 moles of He?
a.
6.02 x 1023 atoms of He
b.
1.03 x 1023 atoms of He
c.
4.00 atoms of He
d.
3.49 x 1024 atoms of He
e.
none of the above
 

 13. 
How many moles of Cu are in 1.48 x 1025 Cu atoms?
a.
0.0408 mol Cu
b.
24.6 mol Cu
c.
1.54 x 1025 mol Cu
d.
6.02 x 1023 mol Cu
e.
none of the above
 

 14. 
What is the mass of one mole of oxygen gas (O2)?
a.
8.00 g
b.
16.0 g
c.
32.0 g
d.
3.01 x 1023 g
e.
6.02 x 1023 g
 

 15. 
What is the mass in grams of 5.40 moles of lithium?
a.
1.29 g
b.
6.94 g
c.
37.5 g
d.
3.25 x 1024 g
e.
none of the above
 

 16. 
How many moles of iron are contained in 1.75 kg of iron?
a.
3.13 x 10-2 mol Fe
b.
3.13 x 10-4 mol Fe
c.
3.13 x 104 mol Fe
d.
31.3 mol Fe
e.
none of the above
 

 17. 
C2H4Cl2 is the formula for two possible molecules. C2H4Cl2 is an example of a(n)
a.
molecular formula.
b.
empirical formula.
c.
condensed formula.
d.
ionic compound formula.
e.
ball and stick model.
 

 18. 
What is the molar mass of ammonium sulfate?
a.
110.0 g/mol
b.
114.1 g/mol
c.
132.1 g/mol
d.
144.6 g/mol
e.
168.9 g/mol
 

 19. 
How many moles are in 4.5 g of AgNO3?
a.
1.3 x 10-3 mol
b.
2.6 x 10-2 mol
c.
0.61 mol
d.
38 mol
e.
7.6 x 102 mol
 

 20. 
A molecule is found to contain 47.35% C, 10.60% H, and 42.05% O. What is the empirical formula for this molecule?
a.
C2H6O
b.
C3H4O2
c.
C3H8O2
d.
C4H6O2
e.
C4H8O3
 



 
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