PRETEST - Gas Laws Multiple Choice: 35 minute time limit



Which of the following gases will have the smallest rate of effusion?

a) H   b) He   c) N   d) Ne   e) CO



A gas mixture contains 2.0 moles of helium and 8.0 moles of carbon dioxide and is held under conditions of standard temperature and pressure. What is the partial pressure of the carbon dioxide?

a) 2.0atm   b) 0.2atm   c) 8.0atm   d) 0.8 atm   e) none of these



The temperature of a fixed mass of gas in a rigid container is decreased from 127.00 degrees Celsius to 27.0 degrees Celsius. The initial pressure was 1000. mmHg. Which is closest to the new pressure, in mmHg, after cooling?

a) 250   b) 500   c) 750   d) 900   e) 1330





A gas is collected over water at a temperature where the vapor pressure of water is known to be 25.0 mmHg. The total pressure recorded in the container is 775.0 mmHg, what is the pressure of the “dry” gas, in mmHg, being collected?

a) 825   b) 800   c) 775   d) 750   e) 725





2.00 moles of a gas are contained in a 2.00 liter vessel at a temperature of 300. degrees Celsius at a pressure of 10.00 atm. The gas is allowed to expand to a new volume of 8.00 liters, but at the same time maintaining the original temperature. What is the new pressure?

a) 10.0 atm   b) 7.50 atm   c) 5.00 atm   d) 2.50 atm   e) 1.25 atm   





A gas that is confined in a rigid container is heated. Which of the following statements is true?

a)       the kinetic energy of the gas particles will decrease

b)       the pressure will increase

c)       the density will decrease

d)       the number of moles of gas will increase

e)       the volume will increase



A gas is held under conditions of standard temperature and pressure. It is found that 44.0 grams of the gas occupies a volume of 22.4 L under these conditions. What is the gas?

a) CO2   b) Cl2      c) F2   d) N2 e) O2





A mixture of gases at a constant temperature includes equal numbers of moles of each of the following. Carbon dioxide, Helium, Neon, Oxygen and Nitrogen. Which gas has the lowest µrms?

a) He   b) Ne   c) O2   d) N2   e) they all are the same



Under what conditions do the assumptions associated with the application of an ideal gas hold true?

a)       low pressure and high temperature

b)       high pressure and large volume

c)       large volume and high temperature

d)       small volume and high temperature

e)       high pressure and low temperature



A gas is heated from 23.000 degrees Celsius to 127.0 degrees Celsius at a constant pressure of 10.00 atm. If the initial volume is V, which equation will best identify the new volume?

a)       (20/123) ×V

b)       (123/20) ×V

c)       (296/400) ×V

d)       (400/296) ×V

e)       none of these





Which assumption is part of the kinetic molecular theory?

a)       the particles in a gas have a distinct volume measured in mL

b)       the particles in a gas attract one another via intermolecular forces

c)       the particles in a gas collide and emit energy to the surroundings

d)       the speed of the particles in a gas is directly proportional to the Kelvin temperature

e)       the particles in a gas can be compressed



For a substance that remains a gas under the conditions listed,  deviation from the ideal gas law would be most pronounced at


A)-100 C and 5.0 atm

B) -100 C and 1.0 atm

C) 0 C and 1.0 atm

D) 100 C and 1.0 atm

E)  100 C and 5.0 atm



Look at the picture below, illustrating the volume and pressure of three separate, closed containers, all at the same temperature:



  2.0L                 2.0L             1.0L

  2.0atm              2.0atm         1.0atm



After stopcocks of all three containers are opened, which is closest to the pressure inside the system (ignore the small volume of the connective capillary tubing).

a)       1.0atm

b)       1.5atm

c)       1.8atm

d)       2.0atm

e)       2.2atm



A hot-air balloon rises. Which is the best explanation for this observation?

a)       the pressure on the walls of the balloon increases with increasing temperature

b)       the difference in temperature between the air inside and outside the balloon produces convection currents

c)       the cooler air outside the balloon pushes in on the walls of the balloon

d)       the rate of diffusion of cooler air is less than that of warmer air

e)       the density inside the balloon is less than that of the surrounding air





A rigid metal tank contains helium gas. Which applies to the gas in the tank when some helium is removed at constant temperature?

a)       the volume of the gas decreases

b)       the pressure of the gas decreases

c)       the average speed of the gas molecules decreases

d)       the total number of gas molecules remains the same

e)       the average distance between the gas molecules decreases



Equal numbers of moles of He(g), Ar(g), and Ne(g) are placed in a glass vessel at room temperature. If the vessel has a pinhole-sized leak, which of the following will be true regarding the relative values of the partial pressures of the gases remaining in the vessel after some of the gas mixture has effused?

a)       PHe> PNe > PAr

b)       PAr > PNe > PHe

c)       PNe > PAr > PHe

d)       PAr > PHe > PNe

e)       PNe = PHe = PAr





Which gas deviates LEAST from ideal behavior?

a) SO2   b) Ne   c) CH4   d) N2   e) H2




Approximately what volume do 3.0 moles of Kr gas occupy at STP?

a)       22.4 L

b)       44.8 L

c)       67.2 L

d)       89.6 L

e)       none of the above



19 – 21.

Questions 19-21 refer to the following gases at 0˚C and 1 atm.

a)       Ne

b)       Xe

c)       H2

d)       CO2

e)       NO


19)    Has an average atomic or molecular speed closest to that of N2 molecules at 0˚C and 1atm.

20)    Has the smallest density

21)    Has the slowest rate of effusion through a pinhole





A flask contains 0.50 mole of SO2(g), 1.50 mole of CH4(g) and 1.0mole of O2(g). The total pressure of the gases in the flask is 1000mmHg. Which is closest to the partial pressure of the O2 (g) in the flask?


a)       800 mmHg

b)       667 mmHg

c)       500 mmHg

d)       333 mmHg

e)       160 mmHg






What volume of O2(g) is required to react with excess CS2(l) to produce 10.0L of CO2(g)? (Assume all gases are measured at 0˚C and 1atm.)


a)       30L

b)       10L

c)       1/3 x 22.4L

d)       2 x 22.4L

e)       10 x 22.4L



Butane gas, C4H10, burns in excess oxygen gas. When the equation for this reaction is correctly balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O2 is


a)       7

b)       9

c)       13

d)       17

e)       26



An 11.2L container will hold about 8.5g of which of the following gases at 0˚C and 1atm?


a) SO2

b) N2

c) CO2

d) C4H8

e) NH3


















Effusion/diffusion: 1, 15, 21

Dalton: 2, 4, 22

Gay lussac: 3

Charles: 5, 10

KMT: 6, 11, KTM, temp relates to KE 14

PvnRT solving for MM (ez with 22.4): 7

Vrms: 8, 19

Bulbs of gas mixing w/ Partial pressures/Dalton: 12

density of gases, hot air balloon: 13, 20

Deviation from ideal gas behavior: 9, 16

Volume of gas at STP: 18, 25 (but asked differently)

Gas stoich 23




1)       e

2)      d

3)      c

4)      d

5)      d

6)      b

7)      a

8)      c

9)      a

10)  d

11)  d

12)  a

13)  c

14)  e

15)  b

16)  b

17)  e

18)  c

19)  e

20)  c

21)  b

22)  d

23)  a

24)  c

25)  e