Chapter 3 Self-Test Questions with Answers

1.  Rewrite these measurements in scientific notation:

a)  0.000758 = 7.58 x 10^-4

b)  4,573,000 = 4.573 x 10⁶

c)  0.3438 = 3.438 x 10^-1

2.  Give the number of significant figures in these measurements.

a)  0.042 L ____2______

b)  78.00 m ____4_____

c)  320 g _____2______

3.  Round off  the following numbers correctly.

a)  Round off 8670 km to two significant figures _____8700 km____

b)  Round off 0.01025 m to three sig. figs. ____0.0103 m_____

c)  Round off 7.013 g to three sig. figs. ____7.01 g______

d)  Round off 0.003629 mm to three sig. figs. ____0.00363 mm_____ 

4.  List and define the SI prefixes you are required to memorize (p. 74).

1 Mm = 10⁶ m;  1 km = 10³ m;  10 dm = 1 m;  100 cm = 1m;  1000 mm = 1 m; 10⁶ mm = 1m;  10⁹ nm = 1m;  10¹² pm = 1m

5.  Express 1.45 x 10⁸ pm in mm.

1.45 x 10^-1 mm

6.  Calculate the density of an 18.0g sample of a piece of metal has a volume of 3.2 mL.  Give answer with correct units and sig. figs.

 density = 5.6 g/mL

7.  A sample of limestone is 25.3 % calcium, 30.3% oxygen and 7.4% carbon by mass. The rest is just “stuff,” that we are not interested in.  A student finds a certain lump of this limestone has a mass of 275.6g.

a)  Calculate the mass of calcium, oxygen and carbon in the limestone.  mass Ca = 69.7 g;  mass O = 83.5 g;  mass C = 20.

b)  Calculate the mass of “stuff.”  mass of "stuff" = 102 g