Chapter 3 Practice #2                                                              Name ____________________________________

1. Explain why the following statements are true, describing which numbers are significant, and which are not.

A. The measurement 90.7 g has three significant figures.

B. The measurement 0.0742 L has three significant figures.

C. The measurement 18200 m has three significant figures.

D. The measurement 18.200 seconds has five significant figures.

2. Write the number of significant figures in the following measurements.

_____ A.      2.708

_____ B.       50.007

_____ C.       0.00045

_____ D.      589000

_____ E.       50800

_____ F.        789.006

_____ G.      507.7800

_____ H.      0.00480

_____ I.         540300

_____ J.         287.345

_____ K.      16.3050

_____ L.       3000010

_____ M.     0.00458

_____ N.      6.38 x 109

_____ O.      4.678 x 1022

_____ P.        3.67 x 10-4

_____ Q.      0.000000875

_____ R.       3322.008

_____ S.        4506.003

_____ T.        56.000

_____ U.      30.230

3. Round 80.45 to

a)      3 significant figures                      b) 2 significant figures                        c) 1. significant figure

4. Round the following numbers to three significant figures

_____________ A.  50.63

_____________ B.   1823

_____________ C.   1.823 x 103

_____________ D.  08129

_____________ E.       .004536

_____________ F.        4.5636 x 10-3

_____________ G.      12.98

_____________ H.      13.02

_____________ I.     129.8

_____________ J.     1.2046

_____________ K.  120.46

_____________ L.   12.04

5. Matching: Match each description in Column B to the correct term in Column A.

Column A

_____ 1. accuracy

_____ 2. measurement

_____ 3. precision

_____ 4. scientific notation

_____ 5. experimental value

_____ 6. significant figures

Column B

a. measure of how close a series of measurements are to one another

b. measure of how close a measurement comes to the actual value

c. digits in a measurement that are known plus one that is estimated

d. a value determined in the laboratory e. a quantity that has both a number and a unit

f. a method of expressing numbers as a product of a coefficient and a power of 10.

6. Use your calculator to answer the following, using the correct significant figures

A. 2.345 + 6.487 =                                               F. 68.439 - 54.1 =

B. 2.7 x 104  + 3.67 x 104 =                                         G. 7.8 x 106  - 2.4 x 105 =

C.  8.4 x 10-4  + 6.89 x 10-4 =                                     H.  2.7 x 10-4  - 3.67 x 10-5 =

D. 456 x 21 =                                             I. 3200 x 460  =

E.                                                  J.