Name: ___________________________________    Date: ______________



Practice Test 4



1.
True or false? One atomic mass unit (amu) is the mass (in grams) of one mole of the substance.
A. True
B. False


2.
True or false? The formula of a compound that expresses the smallest whole-number ratio of the atoms present is called the empirical formula.
A. True
B. False


3.
3.1 moles of oxygen atoms represent
A.
1.0 102 g
B.
1.0 g
C.
1.9 1024 atoms
D.
5.0 101 atoms
E.
none of these


4.
What is the mass of 15 atoms of copper in grams?
A.
63.5 g
B.
2.49 × 10–23 g
C.
953 g
D.
1.42 × 1023 g
E.
1.58 × 10–21 g


5.
Calculate the mass of 21.7 moles of He.
A.
25.7
B.
5.42
C.
1.31 × 1025
D.
86.9
E.
6.02 × 1023


6.
3.67 moles of water weighs
A.
2.04 × 10–1 g
B.
66.1 g
C.
4.91 g
D.
21.8 g
E.
71.8 g


7.
25.8 g of Cu represents how many moles?
A.
1.64 × 103 mol
B.
2.46 mol
C.
0.406 mol
D.
1.55 × 1025 mol
E.
none of these


8.
29.3 g of Ni represents how many atoms?
A.
0.499 atoms
B.
1.76 × 1025 atoms
C.
4.87 × 10–23 atoms
D.
2.86 × 10–21 atoms
E.
3.01 × 1023 atoms


9.
A sample containing 1.20 mol of zinc has a mass of ________ g.
A.
1.84 × 10–2
B.
54.5
C.
78.5
D.
66.6
E.
7.23 × 1023


10.
A 2.46-mol sample of Zr represents how many atoms?
A.
4.09 × 10–24 atoms
B.
1.48 × 1024 atoms
C.
2.45 × 1023 atoms
D.
1.35 × 1026 atoms
E.
2.70 × 10–2 atoms


11.
A sample containing 0.382 mol of sodium has a mass of ________ g.
A.
1.66 × 10–2
B.
6.02 × 101
C.
23.372
D.
2.30 × 1023
E.
8.78


12.
The molar mass of magnesium hydroxide, Mg(OH)2 is
A.
41.3 g/mol
B.
56.3 g/mol
C.
34.0 g/mol
D.
82.6 g/mol
E.
58.3 g/mol


13.
4.45 g of water contains how many molecules of water?
A.
1.49 × 1023
B.
0.247
C.
2.44 × 1024
D.
2.68 × 1024
E.
1.35 × 1023


14.
Convert: 10.7 g CO = _____________ molecules CO
A.
6.44 × 1024
B.
4.98 × 10–22
C.
3.00 × 102
D.
1.78 × 10–23
E.
2.30 × 1023


15.
Convert: 1.706 mol Mg(NO3)2 = ______________ g Mg(NO3)2
A.
253.1
B.
1.150 × 10–2
C.
86.95
D.
225.8
E.
none of these


16.
A 44.7-g sample of H2O contains how many molecules of water?
A.
2.69 × 1025 molecules
B.
8.05 × 102 molecules
C.
1.49 × 1024 molecules
D.
1.34 × 10–21 molecules
E.
none of these


17.
True or false? The mole can be defined as the number equal to the number of oxygen atoms in 32.00 g of oxygen.
A. True
B. False


18.
Determine the percentage composition (by mass) of oxygen in NH4NO3.
A.
72.68 %
B.
59.96 %
C.
19.99 %
D.
99.89 %
E.
33.30 %


19.
Determine the percentage composition (by mass) of tin in SnF2 to three significant figures.
A.
96.2 %
B.
60.2 %
C.
86.2 %
D.
61.0 %
E.
75.7 %


20.
The mass percent of hydrogen in NH4Cl is
A.
26.2 %
B.
2.00 %
C.
7.54 %
D.
none of these


21.
A compound contains 25.94% N and 74.06% O (by mass). What is the empirical formula?

Answer:


22.
Determine the empirical formula of a compound containing 54.2% F and 45.8% S (by mass).

Answer:


23.
A compound has 40.68% carbon, 5.12% hydrogen, and 54.20% oxygen (by mass). Calculate its empirical formula.

Answer:


24.
How many grams of F2 are there in 2.38 mol F2?
A.
0.0626 g
B.
45.2 g
C.
16.0 g
D.
90.4 g
E.
none of these


25.
The number of grams in 3.54 mol of sodium carbonate is
A.
29.9 g
B.
0.0334 g
C.
294. g
D.
375. g
E.
none of these


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