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2nd Semester: Chemistry Weekly Quiz #7 (2/20 - 2/23) - Chapter 6
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This quiz can be taken multiple times BUT the first attempt is the score I will record. (this will be for accuracy)
Make sure to double check your answers if you have used a paper quiz. The choices will be the same but the answers will
be different.
1. How many GRAMS of neon are present in 2.71 x 10 24 atoms? (1 point)
90.9 g
4.5 x 10 47 g
4.5 g
9.09 x 10 48 g
2. Calculate the molecular formula of a compound with the empirical formula CH 2 O and a molar mass of 150 g/mol.
(1 point)
C2H 4O2
C3H 6O3
C4H 8O4
C 5 H 10O 5
C 6 H 12O 6
3. Acetylene gas is 92.3 % carbon and 7.7 % hydrogen (by mass), and its molar mass is 26 g/mol. What is its
molecular formula? (1 point)
CH
C2H 2
CH 4
C4H 4
none of these
4. Which of the following has the largest percent by mass of carbon? (1 point)
CaCO 3
CO2
CH 4
NaHCO 3
5. An avagadro's constant amount of any element is equivilant to (1 point)
the atomic number of that element
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the mass number of that element
6.022 x 10 23 particles
100 g of that element
6. Calculate the mass of 20.0 moles of He (1 point)
5.00
1.00
1.20 x 10 25
80.1
6.02 x 10 23
7. The mass of exactly 5 mol of cesium is (1 point)
664.5 g
132.9 g
6.02 x 10 23 g
5g
8. A quantity of sodium (atomic mass 22.99 amu) contains 6.02x10 23 atoms. The Mass of the sodium is (1 point)
3.88 g
not determinable
6.02x10 23
22.99 g
9. The mass percent of nitrogen in NH4 Cl is (1 point)
16.7 %
25.0 %
26.2 %
none of these
10. How many moles of NH3 are present in 107.1 g? (1 point)
0.1623 mol
3.614 mol
6.289 mol
107.1 mol
11. Choose the pair of compounds with the same empirical formula. (1 point)
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C 2 H 2 and C 6 H 6
NaHCO 3 and Na 2 CO3
K 2 CrO4 and K 2 Cr 2 O 7
H 2 O and H 2 O 2
12. The mass of a sample of nickel is 11.74 g. It contains (1 point)
1.174 x 10 23 atoms
1.205 x 10 23 atoms
1.869 x 10 23 atoms
3.256 x 10 23 atoms
13. Calculate the number of moles of water molecules of 25.0 g of water. (1 point)
4.17 mol
6.98 mol
0.720 mol
1.38 mol
2.78 mol
14. The molar mass of calcium phosphate is (1 point)
324.99 g/mol
310.18 g/mol
175.13 g/mol
135.05 g/mol
none of these
15. Which of the following has the empirical formula CH 2 ? (1 point)
C2H 6
H 2 CO3
C6H 6
C 6 H 12
C2H 4O
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