2.2: Answer Key
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1) No, it is not a proper answer; you do not know whether the professor meant homework problem number 20 or 20 homework problems. Twenty is a quantity and does not make sense without a unit
3)
Middle Zeros: Zeros that appear between other nonzero digits are ALWAYS significant.
Leading Zero: Zeros that appear in front of all nonzero digits are NEVER significant.
Trailing Zero with a decimal point: Trailing zeros in a number with a decimal point are significant.
Trailing Zero without a decimal point: Trailing zero in a number without a decimal points are ambiguous.
5) A conversion factor is a fraction whose numerator and denominator. The system is set up will result in the units in numerator and denominator cancels leaving behind the desire unit.
Scientific Notation
7) a)1.0000 x 108 b) 4.970 x 10-4 c)3.001 x 101 d) 2.500 x 103
9) a) 7.36350 x 105 b)3.9 x 10-3 c) 2.500 x 103 d) 4.78 x 10-1
11) a) 86200 b) 0.0055 c) 0.00000102 d) 0.000000000603
13) a) 4700 b) 7.410 x 103 c) 0.00093 d) 4.5 x 10-3
15) a) 840,000 b) 5.13 x 102 c) 0.00000630 d) 2.50 x 10-1
Significant Figures
17) a) 6.46 cm b) 33.5 mL c) 6.28 mL
19) a) 6 SF all non-zeros are significant
all leading zeros are not significant
all middle zeros are significant
all trailing zeros with a decimal point are significant
b) 6 SF all non-zeros are significant
all middle zeros are significant
c) 6 SF all non-zeros are significant
all trailing zeros with a decimal point are significant
d) 3 SF all non-zeros are significant
all leading zeros are not significant
21) a) 6 SF all non-zeros are significant
all leading zeros are not significant
all middle zeros are significant
all trailing zeros with a decimal point are significant
b) 6 SF all non-zeros are significant
all middle zeros are significant
c) 6 SF all non-zeros are significant
all trailing zeros with a decimal point are significant
d) 3 SF all non-zeros are significant
all leading zeros are not significant
23) a) 5 SF b) 4 SF c) 4 SF d) 4 SF
Rounding
25) a) 24.6 b) 0.342 c) 4.35 x 104 d) 7.00 x 103
27) a) 5.65 x 101 b) 8.90 x 108 c) 1.00 x 106 d) 0.984
29) a) incorrect; 4.56 x 103 b) incorrect; 8.51 x 103 c) correct d) incorrect; 0.0531
31) b) 216.4, 2.2 x 102, 2 x 102
c) 0.3668, 0.37, 0.4
d) 0.008889, 0.0089, 0.009
33) b) 654.9, 6.5 x 102, 7 x 102
c) 0.7513, 0.75, 0.8
d) 0.007778, 0.0078, 0.008
Significant Figures in Calculations
35) a) 4986.2 b) 1.1 c) correct d) 0.154
37) a) 55 b) correct c) 0.86 d) 0.001
39) a) 48 b) 2597 c) correct d) 0.009
41) a) correct b) 6.220 x 103 c) 136 d) 4.5315
Unit Conversion
43) a) 1.000 x 106 mg b) 6.981 x 10-6 m c) 1.5 x 10-2 L d) 3.45 x 103 mm
45) a) 3.4 x 104g b) 7.53934 x 10-6 m c) 3.6 x 103 cL d) 1.09 x 103 mm
47) a) 4.76 x 104 mm b) 6.71 kg c) 0.248 mi d) 30.5 cm
49)
|
m |
km |
mm |
nm |
pm |
|
6.02 x10-5 m |
6.02 x 10-8 km |
6.02 x 10-2 mm |
6.02 x 104 nm |
6.02 x 107 pm |
|
2.53 x 10-11 m |
2.53 x 10-14 km |
2.53 x 10-8 mm |
0.0253 nm |
25.3 pm |
|
2.25 x 10-7 m |
2.25 x 10-10 km |
0.000225 mm |
225 nm |
2.25 x 105 pm |
|
8.22 m |
8.22 x 10-3 km |
8.22 x 103 mm |
8.22 x 109 nm |
8.22 x 1012 pm |
|
4.20 x 102 m |
0.42 |
4.2 x 105 mm |
4.2 x 1011 nm |
4.2 x 1014 pm |
51)
|
m |
km |
mm |
nm |
pm |
|
1.88 x10-5 s |
1.88 x 10-8 km |
1.88 x 10-2 mm |
1.88 x 104 nm |
1.88 x 107 pm |
|
1.43 x 10-11 m |
1.43 x 10-14 km |
1.43 x 10-8 mm |
0.0143 nm |
14.3 pm |
|
3.65 x 10-7 m |
3.65 x 10-10 km |
0.000365 mm |
365 nm |
6.65 x 106 pm |
|
6.34 m |
6.34 x 10-3 km |
6.34 x 103 mm |
6.34 x 109 nm |
6.34 x 109 pm |
|
6.9 x 102 m |
6.9 km |
6.9 x 105 mm |
6.9 x 108 nm |
6.9 x 1011 pm |
Unit Raised to a Power
53) a) 3.5 x 102 in2 b) 2.2 x 101 ft2 c) 3.1 yd3
55) a) 5.33 x 103 in2 b) 3.44 x 106 mm c) 3.44 x 10-6 km
57) a) 2.09 x 104 in2 b) 1.35 x 107 mm2 c) 1.35 x 10-5 km
Density
59) 11.33 g/mL, yes
61) a) 2.34 x 103 g b) 69.1 cm3
63) a) 6.894 x 103 g b) 70.76 cm3
Cumulative Problems
65) $63.54
67) 6.52 x 103 h
69) 32.5 lb of apples
