Chem20, Elementary Chemistry
Chapter Two
58.) Perform each calculation to the correct number of significant figures. a.) 89.3 (3 sig. figs.) x 77.0 (3 sig. figs.) x 0.08 (1 sig. fig) = 550  600 (1 sig. fig.) b.) (5.01

10
5
) (3 sig. figs.) ÷ (7.8

10
2
) (2 sig. figs.) = 642  640 (2 sig. figs) c.) 4.005 (4 sig. figs.) x 74 (2 sig. figs.) x 0.007 (1 sig. fig.) = 2.0  2 (1 sig. fig.) d.) 453 (3 sig. figs.) ÷ 2.031 (4 sig. figs.) = 223.0  223 (3 sig. figs.)
66.) Perform each calculation to the correct number of significant figures. a.) (1.7

10
6
÷ 2.63

10
5
) + 7.33 =
(6.46 (2 sig. figs) ) + 7.33 = 13.79 (1 decimal place)  13.8
b.) (568.99 – 232.1) ÷ 5.3
(336.89 (1 decimal place) ) ÷ 5.3 = 63.5 (2 sig. figs.)  64 c.) (9443 + 45 – 9.9) x 8.1

10
6
(9478.1 (ones position) ) x 8.1  10
6
= 7.67  10
10
(2 sig. figs.)  7.7

10
10 d.) (3.14 x 2.4367) – 2.34
(7.651 (3 sig. figs.) ) – 2.34 = 5.311 (2 decimal places)  5.31
72.) Perform each conversion within the metric system. a.) 1.08 Mm to kilometers
0 m
0 m
m
m
0 m b.) 4.88 fs to picoseconds
1.08

10
3
km
s c.) 7.39  10
0
-
s
11
s
s
0
- 2
s
4.88
m to gigameters

10
-3
ps
0 m
m
0 m
7.39 d.) 1.15

10
-10
m to picometers

10
2
Gm
0
- 0
m
m
0
- 2
m
1.15

10
2
pm
83.) A runner wants to run 10.0 km. She knows that her running pace is 7.5 mi/hr. How many minutes must she run?
0 0 m
mi
m
hr
mi
0 min
hr
49.6
 50. or 5.0

10
1
minutes (2 sig. figs. from 7.5)

116.) A hybrid SUV consumes fuel at a rate of 12.8 km/L. How many miles can the car travel on
22.5 gallons of gasoline?
22 al
al
2 m mi
m
677.0  677 miles