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Per 2 Chapter 6 Prep Test

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

 1. 
The number of atoms in a mole of any pure substance is called
a.
its atomic number.
c.
its mass number.
b.
Avogadro’s number.
d.
its gram-atomic number.
 

 2. 
What can be said about 1 mol Ag and 1 mol Au?
a.
They are equal in mass.
b.
They contain the same number of atoms.
c.
Their molar masses are equal.
d.
They have the same atomic mass.
 

 3. 
An Avogadro’s number of any element is equivalent to
a.
the atomic number of that element.
c.
6.022 ´ 1023 particles.
b.
the mass number of that element.
d.
12 g of that element.
 

 4. 
Using a periodic table, what is the average atomic mass of zinc?
a.
69.723 amu
c.
63.546 amu
b.
58.693 amu
d.
65.39 amu
 

 5. 
The atomic mass of hydrogen is 1.008 amu. The reason that this value is not a whole number is that
a.
hydrogen only exists as a diatomic molecule.
b.
the mass of hydrogen is the sum of the masses of the protons and electrons in the atom.
c.
the mass of a proton is not exactly equal to 1 amu.
d.
hydrogen has more than one isotope.
 

 6. 
A chemical formula includes the symbols of the elements in the compound and subscripts that indicate
a.
the number of formula units present.
b.
the number of atoms or ions of each type.
c.
the formula mass.
d.
the charges on the elements or ions.
 

 7. 
A formula that shows the simplest whole-number ratio of the atoms in a compound is the
a.
molecular formula.
c.
structural formula.
b.
ideal formula.
d.
empirical formula.
 

 8. 
To determine the molar mass of an element, one must know the element’s
a.
Avogadro number.
c.
number of isotopes.
b.
atomic number.
d.
average atomic mass.
 

 9. 
What is the molar mass of magnesium?
a.
12.00 g
c.
24.305 g
b.
26.982 g
d.
22.990 g
 

 10. 
What is the empirical formula for a compound that is 31.9% potassium, 28.9% chlorine, and 39.2% oxygen?
a.
KClO2
c.
K2Cl2O3
b.
KClO3
d.
K2Cl2O5
 

 11. 
A compound contains 64 g of O and 4 g of H. What is the empirical formula for this compound?
a.
H2O
c.
H4O4
b.
H2O2
d.
HO
 

 12. 
A molecular compound has the empirical formula XY3. Which of the following is a possible molecular formula?
a.
X2Y3
c.
X2Y5
b.
XY4
d.
X2Y6
 

 13. 
A compound’s empirical formula is NO2. If the formula mass is 92 amu, what is the molecular formula?
a.
NO
c.
NO2
b.
N2O2
d.
N2O4
 

 14. 
What is the sum of the atomic masses of all the atoms in a formula for a compound?
a.
molecular mass
c.
atomic mass
b.
formula mass
d.
actual mass
 

 15. 
What is the formula mass of ethyl alcohol, C2H5OH?
a.
30.33 amu
c.
45.06 amu
b.
33.27 amu
d.
46.08 amu
 

 16. 
The molar mass of LiF is 25.94 g/mol. How many moles of LiF are present in 10.37 g?
a.
0.3998 mol
c.
2.500 mol
b.
1.333 mol
d.
36.32 mol
 

 17. 
How many oxygen atoms are there in 0.500 mol of CO2?
a.
6.02 mc017-2.jpg 1023
c.
15.9994
b.
3.01 mc017-3.jpg 1023
d.
11.0
 

 18. 
If 0.500 mol of Na+ combines with 0.500 mol of Cl– to form NaCl, how many formula units of NaCl are present?
a.
3.01 mc018-2.jpg 1023
c.
6.02 mc018-4.jpg 1024
b.
6.02 mc018-3.jpg 1023
d.
1
 

 19. 
What is the percentage composition of CuCl2?
a.
33% Cu, 66% Cl
c.
65.50% Cu, 34.50% Cl
b.
50% Cu, 50% Cl
d.
47.27% Cu, 52.73% Cl
 

 20. 
The empirical formula is always the accepted formula for a(n)
a.
atom.
c.
molecular compound.
b.
molecule.
d.
ionic compound.
 

 21. 
A positively charged particle with mass 1.673 ´ 10–24 g is a(n)
a.
proton.
c.
electron.
b.
neutron.
d.
positron.
 

 22. 
All atoms of the same element have the same
a.
atomic mass.
c.
mass number.
b.
number of neutrons.
d.
atomic number.
 

 23. 
Atoms of the same element can differ in
a.
chemical properties.
c.
atomic number.
b.
mass number.
d.
number of protons and electrons.
 

 24. 
In determining atomic mass units, the standard is the
a.
C-12 atom.
c.
H-1 atom.
b.
C-14 atom.
d.
O-16 atom.
 

 25. 
The abbreviation for atomic mass unit is
a.
amu.
c.
a.
b.
mu.
d.
m.
 

 26. 
The average atomic mass of an element is the average of the atomic masses of its
a.
naturally occurring isotopes.
c.
nonradioactive isotopes.
b.
two most abundant isotopes.
d.
artificial isotopes.
 

 27. 
A single atom of an isotope does not have a(n)
a.
relative atomic mass.
c.
mass number.
b.
atomic number.
d.
average atomic mass.
 

 28. 
The mass of two moles of oxygen atoms (atomic mass 16 amu) is
a.
16 g.
c.
48 g.
b.
32 g.
d.
64 g.
 

 29. 
How many moles of atoms are in 50.15 g of mercury (atomic mass 200.59 amu)?
a.
0.1001 mol
c.
0.2500 mol
b.
0.1504 mol
d.
0.4000 mol
 

 30. 
The molar mass of MgI2 is
a.
the sum of the masses of 1 mol of Mg and 2 mol of I.
b.
the sum of the masses of 1 mol of Mg and 1 mol of I.
c.
the sum of the masses of 1 atom of Mg and 2 atoms of I.
d.
the sum of the masses of 1 atom of Mg and 1 atom of I.
 

 31. 
A formula that shows the simplest whole-number ratio of the atoms in a compound is the
a.
molecular formula.
c.
experimental formula.
b.
ideal formula.
d.
empirical formula.
 

 32. 
What is the empirical formula for a compound that is 53.3% O and 46.7% Si?
a.
SiO
c.
Si2O
b.
SiO2
d.
Si2O3
 

 33. 
What is the molecular formula of a compound that has a formula mass of 50.48 amu and an empirical formula of CH3Cl?
a.
CHCl
c.
CH3Cl
b.
CH2Cl
d.
CH2Cl2
 

 34. 
Isotopes are atoms of the same element that have different
a.
principal chemical properties.
c.
numbers of protons.
b.
masses.
d.
numbers of electrons.
 

 35. 
The molar mass of CS2 is 76.15 g/mol. How many grams of CS2 are present in 10.00 mol?
a.
0.13 g
c.
10.00 g
b.
7.614 g
d.
761.5 g
 

 36. 
The molar mass of NH3 is 17.03 g/mol. How many moles of NH3 are present in 107.1 g?
a.
0.1623 mol
c.
6.289 mol
b.
3.614 mol
d.
107.1 mol
 

 37. 
What is the mass of 0.240 mol glucose, C6H12O6?
a.
24.0 g
c.
180.16 g
b.
43.2 g
d.
750. g
 

 38. 
How many Cl– ions are present in 2.00 mol of KCl?
a.
1.20 mc038-2.jpg 1024
c.
2.00
b.
6.02 mc038-3.jpg 1024
d.
0.5
 

 39. 
Which of the following compounds have the same empirical formula?
a.
NO2 and N2O5
c.
C5H10 and C3H6
b.
SO3 and NO3
d.
H2O and H2O2
 



 
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