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Chemistry 12: College Preparation Unit 2 Self Quiz - 2.1 - 2.4



Modified True/False
Indicate whether the sentence or statement is true or false.  If false, change the identified word or phrase to make the sentence or statement true.
 

 1. 

In a balanced chemical equation, the total mass of reactants equals the total mass of products. ____________________

 

 2. 

One mole of NH3(g) molecules contains one mole of nitrogen atoms and three moles of hydrogen atoms. ____________________

 

 3. 

One mole of CO2(g) molecules contains 6.02 ´ 1023 CO2(g) molecules. ____________________

 

 4. 

The atomic mass unit is equal to the mass of 12 carbon-12 atoms. ____________________

 

 5. 

The isotopes of an element differ by the number of protons in the nucleus. ____________________

 

 6. 

If the atomic mass of chlorine is 35.5 u/atom, the molar mass of chlorine is 35.5 g/mol. ____________________

 

 7. 

Molecular elements contain two or more atoms of the same element. ____________________

 

 8. 

The law of constant composition states that compounds contain atoms in fixed proportions. ____________________

 

 9. 

A combustion analyzer measures the molar mass of a compound. ______________________________

 

 10. 

The information provided by a combustion analyzer and mass spectrometer may be used to determine the molecular formula of a compound. ____________________

 

 11. 

If the molecular formula of a compound is C3H8NS, then its empirical formula is also C3H8NS. ____________________

 

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

 12. 

What amount of carbon dioxide is in 17.6 g of carbon dioxide?
a.
5.87 mol
c.
0.40 mol
b.
2.5 mol
d.
0.55 mol
 

 13. 

The molar mass of methanol, CH4O(l), is
a.
28.0 g/mol
c.
29.0 g/mol
b.
31.0 g/mol
d.
32.0 g/mol
 

 14. 

The molar mass of calcium phosphate, Ca3(PO4)2(s), is
a.
278 g/mol
c.
247 g/mol
b.
310 g/mol
d.
199 g/mol
 

 15. 

The mass of 3.75 mol of KF(s) is
a.
3.75 g
c.
217.8 g
b.
58.1 g
d.
108.9 g
 

 16. 

What amount of iron is in 5.00 mol of FeO(s)?
a.
5.00 mol
c.
1.00 mol
b.
10.00 mol
d.
2.50 mol
 

 17. 

How many molecules of NO(g) are in 16.0 g of NO(g)?
a.
3.21 ´ 1023
c.
1.81 ´ 1025
b.
9.63 ´ 1024
d.
6.02 ´ 1023
 

 18. 

Which of the following elements contains the greatest number of atoms in a 5.00-g sample?
a.
lithium
c.
potassium
b.
sodium
d.
rubidium
 

 19. 

Which of the following samples contains the same number of atoms as 40.00 g of Ne(g)?
a.
4.00 g of He(g)
c.
40.00 g of C(s)
b.
24.00 g of Mg(g)
d.
80.00 g of Ar(g)
 

 20. 

How many molecules are in 0.25 mol O2(g)?
a.
12 ´ 1023
c.
3.0 ´ 1023
b.
6.0 ´ 1023
d.
1.5 ´ 1023
 

 21. 

What is the mass of iron in 1.00 mol Fe2O3(s)?
a.
160 g
c.
72.0 g
b.
112 g
d.
56.0 g
 

 22. 

How many oxygen atoms are in 49.0 g of H2SO4(aq)?
a.
2.4 ´ 1024
c.
3.01 ´ 1023
b.
6.02 ´ 1023
d.
1.2 ´ 1024
 

 23. 

Which of the following statements is incorrect?
a.
One mole of ozone has a mass of 48.0 g.
b.
One mole of methane, CH4(g), contains 6.02 ´ 1023 carbon atoms.
c.
12.01 g of carbon has the same number of atoms as 12.01 g of nitrogen.
d.
One mole of a substance is the amount of the substance that has the same number of entities as 12.00 g of carbon-12.
 

 24. 

Which of the following entities has the greatest mass?
a.
one atom of aluminum
c.
one atom of phosphorus
b.
one molecule of fluorine
d.
one molecule of methane
 

 25. 

A mass spectrometer measures
a.
the percentage of elements in a compound
b.
the molar mass of a compound
c.
the number of ions in an ionic compound
d.
the charge on an ion
 

 26. 

The empirical formula of a compound is CH. Its molar mass is 78.0 g/mol. What is its molecular formula?
a.
CH
c.
C12H12
b.
C6H6
d.
C2H6
 

 27. 

The percentage composition by mass of a compound is 52.16% carbon, 7.29% hydrogen, and 40.55% nitrogen. Its molar mass is 138.20 g/mol. What is the molecular formula of the compound?
a.
C8H14N2
c.
C6H10N4
b.
C7H12N3
d.
C3H5N2
 

 28. 

What is the percentage by mass of chlorine in hypochlorous acid, HClO(aq)?
a.
46.71%
c.
30.52%
b.
23.40%
d.
67.58%
 

 29. 

What is the percentage by mass of nitrogen in Cu(NO3)2(s)?
a.
14.93%
c.
50.61%
b.
33.88%
d.
44.40%
 

Completion
Complete each sentence or statement.
 

 30. 

The number 6.02 ´ 1023 is equivalent to ____________________ constant.
 

 

 31. 

The term ____________________ specifically refers to the number of moles of chemical entities in a quantity of matter.
 

 

 32. 

When working with chemical entities, the mole is a reasonable quantity because this quantity can be ____________________ and ____________________.
 

 

 33. 

The ____________________ number of an element is equal to the number of protons in the nucleus.
 

 

 34. 

The atomic molar mass of an element is equal to the mass, in grams, of one ____________________ of atoms of the element.
 

 

 35. 

Chemists determine the amount of a chemical entity in a pure sample by measuring the ____________________ of the sample.
 

 

 36. 

The empirical formula of a compound describes the ____________________ ratio of atoms or ions in a compound
 

 



 
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