Houston Community College System
Chemistry 1405
PRACTICE EXAM # 1
HOUSTON COMMUNITY COLLEGE
CHEM 1405
Name: _____________________
Exam # 1 (Chap. 1- 3)
Score:
PART I – Multiple choice: (3 points each)
1. What is the term for an investigation that entails performing an experiment, proposing a hypothesis,
testing the hypothesis, and stating a theory or law?
a) alchemy b) chemistry c) science d) scientific method e) none of the above
Answer …..................
2. What question can we ask in order to distinguish between a theory and a law?
a) Does the statement concern atoms? b) Does the statement concern gases? c) Is the statement
comprehensible? d) Is the statement measurable? e) none of the above
Answer …..................
3. In which of the following industries does chemistry play an important role?
a) agriculture b) medicine c) petrochemical d) pharmaceutical e) all of the above
Answer …......................
4. What subject is referred to as the central science?
a) biology b) chemistry c) geology d) physics e) none of the above
Answer ….....................
5. What is the term for the inexactness of an instrumental measurement?
a) accuracy b) error c) precision d) uncertainty e) none of the above
Answer …...........................
6. What is the term for the gravitational force of attraction between an object and Earth?
a) length b) mass c) volume d) weight e) none of the above
Answer ….....................
7. Which of the following volume instruments has the least uncertainty?
a) buret, ± 0.01 mL b) graduated cylinder, ± 0.5 mL c) hypodermic syringe, ± 0.001 mL d) volumetric
flask, ± 0.05 mL e) volumetric pipet, ± 0.1 mL
Answer …......................
8. How many significant digits are in the volume measurement 50,000 milliliters?
a) 1 b) 2 c) 3 d) 4
Answer ….....................
9. Express 0.000 000 000 000 01 in exponential form.
a) 1x 10–15 b)1x10–14 c) 1x10–1 d) 1x1014 e) none of the above
Answer …..........................
10. One gram of gold contains 3,060,000,000,000,000,000,000 atoms. Express this number of gold
atoms in scientific notation.
a) 3.06 x 1020 b) 3.06 x 1021 c) 3.06 x 1022 d) 30.6 x 1020 e) 30.6 x 1021
Answer …...........................
11. If a marathon race is 26.2 miles, what is the distance in yards?
(Given: 1 mile = 1760 yards)
a) 0.0149 yards b) 67.2 yards c) 46,000 yards d) 46,100 yards e) 46,112 yards
Answer ….....................
12. Which of the following is the basic unit of temperature in the metric system?
a) Celsius degree (°C) b) Fahrenheit degree (°F) c) Kelvin unit (K) d) all of the above e) none of the
above
Answer ….......................
13. Which of the following terms defines the amount of mass in a unit volume?
a) density b) specific mass c) specific gravity d) specific volume e) none of the above
Answer ….............................
14. Which of the following is a unit that expresses the volume occupied by a cube 1 centimeter on a
side?
a) cm2 b) cm3 c) mm2 d) mm3 e) none of the above
Answer …..................
15. What is the symbol for the metric unit micrometer?
a) cm b) mm c) Mm d) µm e) none of the above
Answer ….......................
16. What physical quantity is expressed by the metric unit centimeter?
a) length b) mass c) volume d) density e) none of the above
Answer …...................
17. According to the metric system, 1 _____ = 1,000,000,000 g.
a) Tg b) Gg c) Mg d) ng e) none of the above
Answer …...........................
18. If an automobile airbag inflates in 25 µs, what is the time in seconds?
a) 0.000 025 s b) 0.000 25 s c) 25,000 s d) 25,000,000 s (e)none of the above
Answer …..........................
19. What are the freezing point and boiling point of water on the Fahrenheit scale?
a)
–32°F and 212°F b) 0°F and 100°F c) 0°F and 212°F d) 32°F and 100°F e) 32°F and 212°F
Answer ….......................
20. Which of the following are basic units and symbols in the metric system?
a) centimeter (cm), gram (g), liter (L) b) centimeter (cm), gram (g), milliliter (mL) c) meter (m), gram
(g), liter (L) d) meter (m), gram (g), liter (l) e) The metric system does not have basic units.
Answer ….........................
Part II Show all you work and calculations. Each question carries 8 points.
1. A sample of white gold is: 18.0 grams gold, 3.0 grams silver, 2.0 grams cobalt, and 1.0 gram
platinum by mass. What is the percent of platinum in the sample? (Write your answer to the correct
number of significant figures)
2. If an auto gas tank holds 66 liters, what is the volume in gallons?
(Given: 1 gallon = 3.785 liters) (Write your answer to four significant figures)
3. Convert a) 25 Gigameters to meters b) 10 microseconds to nanoseconds
4. A block of lead has dimensions of 4.5 cm by 5.2 cm by 6.0 cm. The block weighs 1587 g. From this
information, calculate the density of lead. (Write your answer to the correct number of significant
figures)
5. Convert – 45ºC to Fahrenheit scale.
Answer Key:
Multiple Choice
1. d 2. d 3. e 4. b 5. d 6. d 7. c 8. a 9. b 10. b 11. e 12. a 13. a 14. b 15. d 16. a 17. e 18. d 19. e 20.c
1. percent of platinum = [mass of platinum in white gold sample / total mass of sample] x 100
= [ 1 / 18 + 3 + 2 + 1] x 100
= [ 1 / 24] x 100
= 4 % (approximated to one significant figure)
2. Given : 66 liters
Convert: Volume to gallons
1 gallon = 3.785 liters
66 liters
1
1 gallon
3.785 liters
[66 x 1] / 3.785 = 17. 43 gallons
3. a) Given : 25 Gigameters
Convert to : meters
1 Gm = 10 ^ 9 meters
25 Gm
10^9 meters
1
1 Gm
25 x 10^ 9 meters
b) 10 microseconds to nanoseconds
Step 1: Convert 10 microseconds to seconds
Given: 10 microseconds
Convert to : seconds
1 microsecond = 10 ^ -6 seconds
10 microseconds
1
10 ^ -5 seconds
10^- 6 seconds
1 microseconds
Step 2 : Convert seconds to nanoseconds
Given : 10 ^ -5 seconds
Convert to : nanoseconds
1 nanosecond = 10 ^ -9 seconds
10 ^ -5 seconds
1
1 nanosecond
10 ^ -9 seconds
Answer : 10,000 nanoseconds
4. Density = mass / volume
Volume of block = length x width x height
Volume = 4.5 x 5.2 x 6.0 = 140 cubic centimeters
Density = 1587 / 140 = 11 g/mL
5. Formula for converting from celsius to Fahrenheit
(celcius temperature x 9/5) + 32
(-45 x 9/5) + 32
-49 degree Fahrenheit