Practice Questions - Air

1. Which of the following makes up the smallest percentage of the atmosphere?
(A) O₂
(B) N₂
(C) O₃
(D) H₂O
(E) CO₂

2. A hot-air balloon rises. Which of the following is the best explanation for this observation?
(A) The pressure on the walls of the balloon increases with increasing tempearature.
(B) The difference in temperature between the air inside and outside the ballon produces convection currents.
(C) The cooler air outside the balloon pushes in on the walls of the ballon.
(D) The rate of diffusion of cooler air is less than that of warmer air.
(E) The air density inside the ballon is less than that of the surrounding air

3. Which substance bonds more strongly to hemoglobin than oxygen?
(A) SO₂
(B) NO₂
(C) O₃
(D) CO

4. If the average human adult inhales 14 times each minute, and the average volume of gas inhaled each time is 500 mL, how many liters of gas are inhaled in one hour?
(A) 840 L
(B) 420 L
(C) 60 L
(D) 0.5 L

5. Based on your knowledge of the properties of gases, predict what will happen to the density of 100 g of helium gas if the sample is heated from room temperature to 60oC at constant pressure.
(A) remain unchanged
(B) increase
(C) decrease
(D) depends on the air pressure

6. Which statement best explains why air is gaseous?
(A) The atmosphere exerts pressure on all objects in contact with it.
(B) The components of air have very low boiling points.
(C) A decrease of carbon dioxide has occured in the atmosphere recently due to mining.
(D) Various elements and compounds can be separated from samples of air by fractional distillation.

7. What is the number of O₂ molecules in the 2.5 g of O₂ inhaled by the average person in one minute?
(A) 1.9 x 10²²
(B) 3.8 x 10²²
(C) 4.7 x 10²²
(D) 9.4 x 10²²

8. A 5.00 L of gas is at 35^oC and 1.00 atm pressure. What will the volume become if the pressure is increased to 4.00 atm and the temperature remains constant?
(A) 20.0 L
(B) 8.00 L
(C) 1.25 L
(D) 15.0 L

9. You are at the beach on a sunny day. You observe that the sand gets very hot by midday, while the water temperature remains about the same. What is the best explanation for this observation?
(A) The cool breeze makes the water feel colder than the sand.
(B) Sitting on the hotter sand makes the water feel cooler.
(C) Sand both absorbs and gives off heat more readily than does water.
(D) Hotter sand causes a sea breaze to be produced, which cools the water.

10. Which matches the phrase "a hydrogen ion concentration of 10^-7 mol/L"?
(A) a pH of 7
(B) an acidic water solution
(C) a basic water solution
(D) pure rain water

11. Which statement is consistent with the observation that the pressure of the Earth's atmosphere at sea level supports a column of water 10.3 m high?
(A) The atmosphere will also support a column of mercury 10.3 m high.
(B) A 10.3 m high column of water exerts a pressure equal to 760 mm Hg, so the pressure of the atmosphere may be expressed as either 10.3 m H₂O or 760 mm Hg.
(C) The great pressure of the atmosphere is produced by the relatively heavy atoms and molecules that make up the atmosphere.
(D) The atmospheric pressure on top of a high mountain is considerably less than it is at sea level.

12. A rigid metal tank contains oxygen gas. Which of the following applies to the gas in the tank when additional oxygen is added at constant temperature?
(A) The volume of the gas increase.
(B) The pressure of the gas decreases.
(C) The average speed of the gas molecules remains the same.
(D) The total number of gas molecules remains the same.
(E) The average distance between the gas molecules increases.

13. The planet Mars has a surface temperature about forty degrees below that of the Earth. Which statement helps to explain this observation?
(A) The CO₂ and H₂O molecules in the Earth's atmosphere are good absorbers of infrared photons, trapping some of these photons and returning some of them to the Earth's surface. Mars does not have CO2 and H2O in its atmosphere.
(B) CO₂ and H₂O react in the atmosphere of the Earth to produce heat energy which radiates to the Earth's surface as infrared photons, but Mars does not have CO₂ and H₂O in its atmosphere.
(C) Ultraviolet photons break single chemical bonds existing in water molecules in the atmosphere, procing H₂ and O₂ and heat which radiates to the Earth's surface, but Mars does not have water molecules in its atmosphere.
(D) Unlike the Earth's atmosphere, molecular motion in Mars' atmosphere is virtually nonexistent, thus little heat is produced.

14. Electrostatic precipitators work in reducing air pollution because
(A) many pollutants exist as charged ionic particles, or can form charged particles.
(B) precipitaors utilize water as an ionizing catalyst.
(C) precipitators eliminate the need for waste disposal.
(D) some useful products can be obtained from the pollutants collected by the precipitators.

15. Which set of conditions represents the easiest way to liquefy a gas?
(A) low temperature and high pressure
(B) low temperature and low pressure
(C) high temperature and low pressure
(D) high temperature and high pressure

16. At which pressure would a boiling liquid exhibit the lowest temperature?
(A) 380 mm Hg
(B) 760 mm Hg
(C) 1 atmosphere
(D) 2 atmospheres

17. The normal melting point of ice on the Kelvin scale is
(A) 0 K
(B) 32 K
(C) 80 K
(D) 273 K

18. Which sample has molecules having the greatest kinetic energy?
(A) 1.0 liter of oxygen at 20^oC
(B) 2.0 liters of hydrogen at 15^oC
(C) 2.0 liters of oxygen at 5^oC
(D) 1.0 liters of hydrogen at 10^oC

19. How many molecules of the gas NO are contained in 2.0 moles?
(A) (6.0 X 10²³) / 2
(B) 6.0 X 10²³
(C) 2 (6.02) X 10²³
(D) 2 X 22.4

20. What conditions of pressure and temperature are defined as STP?
(A) 1 atm and 0 K
(B) 273 atm and 273 K
(C) 1 atm and 0^oC
(D) 273 atm and 0^oC

21. When air is compressed, it
(A) occupies a larger volume
(B) glows
(C) gets hot
(D) freezes

22. What is the pH of a 0.001 M HCl solution?
(A) 10
(B) 0.001
(C) 3
(D) .-3

23. A mixture of gases is prepared by combining 2 liters of oxygen, 2 liters of nitrogen, and 1 liter of carbon dioxide. Which of the following represents the correct percentages in this mixture by volume?
(A) 20% oxygen, 20% nitrogen, 10% carbon dioxide
(B) 20% oxygen, 79% nitrogen, 1% carbon dioxide
(C) 2% oxygen, 2% nitrogen, 96% carbon dioxide
(D) 40% oxygen, 40% nitrogen, 20% carbon dioxide
(E) none of the above

24. A glass of grapefruit juice, at pH 3, contains _____ H⁺ as a glass of tomato juice, at pH 4.
(A) ten times as much
(B) one-tenth as much
(C) three times as much
(D) half as much
(E) twice as much

25. Which will have the larger mass?
(A) 1 mol of Ar
(B) 2 mol of CO
(C) 1 mol of Sn
(D) 1 mol of N

26. Water boils at 100^oC. Which of the following corresponds to this temperature?
(A) 100 K
(B) 273 K
(C) 373 K
(D) O K
(E) -273 K

27. Which of the following is NOT considered a pollutant?
(A) NO
(B) CO
(C) sulfur dioxide
(D) H₂O
(E) lead

28. Which acid pair is associated with acid rain?
(A) H₂SO₄ and HNO₃
(B) H₂SO₄ and HCl
(C) HNO₃ and H₃PO₄
(D) H₃PO₄ and HCl

29. If the number of hydrogen ions in a solution is increased, the
(A) solution becomes more acidic.
(B) solution becomes more alkaline (basic).
(C) pH of the solution will be increased.
(D) solution is a buffer.

30. The molar mass of a gas with a density of 5.8 grams per liter at 25 °C and 740 mmHg is closest to
(A) 10 g / mol
(B) 20 g / mol
(C) 150 g / mol
(D) 190 g / mol

ANSWERS

1-C 2-E 3-D 4-B 5-C 6-B 7-C 8-C 9-C 10-A 11-B 12-C 13-A 14-A 15-A 16-A 17-D 18-A 19-C 20-C 21-C 22-C 23-D 24-A 25-C 26-C 27-D 28-A 29-A 30-C