Name ___________________________________________ Date ____________ Period ______
CHEMISTRY: GAS LAWS UNIT EXAM PRACTICE
Gases
1. When someone standing at one end of a large room opens a bottle of vinegar, it may take up to
several minutes for a person at the other end to smell it. Gas molecules at room temperature move
at very high velocities, so what is responsible for the delay in detection of the vinegar? (Std 4B)
a. The increase in airspace occupied by vinegar molecules
b. The chemical reaction with nerves, which is slower than other sensory processes
c. Attractive forces between the air and vinegar molecules
d. Random collisions between the air and vinegar molecules
2. Methane (CH4) gas diffuses through the air because the molecules are (Std 4B)
a. Moving randomly
b. Dissolving quickly
c. Traveling slowly
d. Expanding steadily
3. The volume of 400 mL of chlorine gas at 400mmHg is decreased to 200mL at constant temperature.
What is the new gas pressure? (Std 4c)
a. 400 mmHg
b. 300 mmHg
c. 800 mmHg
d. 650 mmHg
4. Standard temperature and pressure (STP) are defined as (Std 4D)
a. 0°C and 1.0 atm pressure
b. 0°C and 273 mmHg pressure
c. 0 K and 1.0 atm pressure
d. 0 K and 760 mmHg pressure
5. Under which of the following sets of conditions will a 0.5 mole sample of helium occupy a volume of
11.2 liters? (Std 4D)
a. 298 K and 0.90 atm
b. 273 K and 1.10 atm
c. 373 K and 0.50 atm
d. 273 K and 1.00 atm
6. What is the equivalent of 423 Kelvin in degrees Celsius? (Std 4E)
a. -223°C
b. -23°C
c. 150°C
d. 696°C
7. What is diffusion?
A. Molecules of gas joining together
B. Gas molecules colliding with each other to produce pressure
C. The process of gas molecules spreading out from high to low concentration
D. Nuclear fusion
8. What happens to the movement of gas molecules when they are heated?
A. molecules move faster
B. molecules move slower
C. molecules move at the same speed
D. molecules don’t move
9. If a sealed bag of chips is left in a hot car, what happens to the volume of bag?
A. volume increases
B. volume decreases
C. volume stays the same
D. cannot be determined
10. A balloon has a volume of 9 L at 300K. What will the volume of the balloon be if the temperature
decreases to 200K?
A. 4.5 L
B. 6 L
C. 18 L
D. 3 L
11. Absolute 0 is:
A. -273ºC
B. 0K
C. both a & b
D. none of the above
12. What causes air pressure?
A. the random motion of molecules and their collisions with the surface of a container
B. diffusion of air molecules from an area of high concentration to an area of low concentration
C. temperature
D. all of the above
(For 8-9) A beach ball has a volume of 2 L at sea level where the pressure is 1.0 atm. You take the
ball to the top of a mountain where pressure is 0.8 atm.
13. What happens to the volume of the ball?
A. volume increases
B. volume decreases
C. volume stays the same
D. cannot be determined
14. Calculate the new volume of the balloon
A. 1.6 L
B. 1 L
C. 2.5 L
D. 2.5 atm.
15. What happens to the pressure of the air inside a flask when the flask is heated?
A. pressure increases
B. pressure decreases
C. pressure stays the same
D. pressure decreases and then increases
16. What volume does 35.0 moles of N2 occupy at STP?