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- 1. Multiple Choice
What is the general formula for the computation of percentage composition of the given element?
% mass of element = mass of element in the compound divided by mass of the compound times 100
% mass of element = mass of element in the compound divided by mass of the compound
% mass of element = mass of element in the compound divided by 100
% mass of element = mass of element in the compound
- 2. Multiple Choice
Which of the following refers to molecular formulas?
Are the formulas showing the type of atoms and number of each atom connected in the molecule.
Are the simplest form of formulas that we can write for a molecule.
A simple molecules like crystalline ionic compounds.
Composed of two or more elements
- 3. Multiple Choice
What is the percent by mass of magnesium in MgO?
20%
40%
50%
60%
- 4. Multiple Choice
What is the percent by mass of chlorine in NaCl?
39%
61%
35%
35%
- 5. Multiple Choice
What is the percent by mass of fluorine in CaF2 (gram-formula mass = 78 g/mol)?
24%
49%
49%
65%
- 6. Multiple Choice
What is the percent by mass of calcium in CaF2 (gram-formula mass = 78 g/mol)?
24%
49%
51%
65%
- 7. Multiple Choice
Find the percent composition of Cu2S?
%Cu= 67.987 %S= 32.013
%Cu= 79.854 %S= 20.145
%Cu= 35.946 %S= 64.054
- 8. Multiple Choice
What is the percent composition of Benzene, C6H6?
C = 50%
H = 50%
C = 85.7 %
H = 14.3%
C = 92.2%
H = 7.8%
C = 71.9%
H = 28.1%
- 9. Multiple Choice
Which element in the compound potassium cyanide, KCN, has a percent composition of 60.97%?
K
C
N
None
- 10. Multiple Choice
What is the mass of one mole of aluminum chloride (remember to determine the correct formula first)?
62.435g
116.399g
133.341g
97.888g
- 11. Multiple Choice
Which of the following is NOT needed to calculate percent composition?
Mass of specific element
Molar Mass
Avogadro's Number
Division
- 12. Multiple Choice
The molar mass of an element is equal to its...
Atomic mass
Atomic number
Oxidation number
Valence electrons
- 13. Multiple Choice
Find the molar mass of KCl
36 g/mol
36 g/mol
74 g/mol
178 g/mol
- 14. Multiple Choice
What is the molar mass of PbSO4
303.3 g/mol
294.7g/mol
163.8g/mol
372g/mol
- 15. Multiple Choice
How many hydrogen atoms are in one formula unit of C2H4O2?
2
1
4
6
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