CHM 2045C Module 6 Sample Exam
Part M: Multiple Choice

1. At constant temperature, the pressure of the gas that is trapped in the end of the J-tube is 760 torr. If h is equal to 50 torr, what is the pressure that is due to the atmosphere?

a.

50 torr

b.

710 torr

c.

760 torr

d.

810 torr

e.

Cannot tell because the temperature is not given.

 

2. Who developed the following relationship: "At constant pressure, the volume of gas is directly proportional to the absolute temperature"?

 

a.

Avogadro

b.

Dalton

c.

Boyle

d.

Charles

e.

Graham

 

3. For an ideal gas, which pair of variables are inversely proportional to each other (if all other factors remain constant)?

a.

P, V

b.

P, T

c.

V, T

d.

n, P

e.

n, V



4. A gas occupies a volume of 1.50 L at 400 mm Hg and 100?C. Which mathematical expression gives the correct volume at 700 mm Hg and 200?C?

 

a.

b.

c.

d.

e.



5. If a certain mass of gas occupies 75 mL at 293 K and 770 mm Hg, what is its volume at STP?

a.

b.

c.

d.

e.

 


6. A given mass of gas in a rigid container is heated from 100?C to 500?C. Which of the following responses best describes what will happen to the pressure of the gas?

a.

The pressure will remain the same.

b.

The pressure will decrease by a factor of five.

c.

The pressure will increase by a factor of five.

d.

The pressure will increase by a factor less than five.

e.

The pressure will increase by a factor greater than five.



7. When ammonium nitrite undergoes decomposition, only gases are produced according to the equation

NH4NO2(s) --> N2(g) + 2H2O(g)

What is the total volume of gases produced at 819 K and 1.00 atm pressure when 128 g of ammonium nitrite undergoes the above decomposition reaction?

a.

3 x 22.4 L

b.

6 x 22.4 L

c.

9 x 22.4 L

d.

12 x 22.4 L

e.

18 x 22.4 L



8. At standard conditions, it was found that 1.12 L of a gas weighed 2.78 g. Its molecular weight is

a.

2.78 g/mol.

b.

27.8 g/mol.

c.

55.6 g/mol.

d.

111 g/mol.

e.

Not enough information is given to solve this problem.



9. At 27?C and 1.00 atm, the density of a gaseous hydrocarbon is 1.79 gL-1. The hydrocarbon is

a.

CH4.

b.

C2H4.

c.

C2H6.

d.

C3H8.

e.

C4H8.


10. At 27?C and 0.45 atm, an unknown pure gas has a density of 1.30 g/L. Which of the following gases could be the unknown gas?

a.

NF3

b.

Ne

c.

CO2

d.

CH4

e.

N2

 

 


11. A mixture of the gases nitrogen, oxygen, and carbon dioxide at 27?C and 0.50 atmosphere pressure occupy a volume of 492 ml. How many moles of gas are there in this sample?

a.

0.010

b.

1/9

c.

7.6

d.

10

e.

Cannot be determined since it is a mixture.


12. A mixture consisting of 0.100 moles of N2, 0.050 moles of O2, 0.200 moles of CH4, and an unknown amount of CO2 occupy a volume of 9.60 L at 27?C and 1.00 atmosphere pressure. How many moles of CO2 are there in this sample?

a.

0.040 moles

b.

0.050 moles

c.

0.100 moles

d.

0.390 moles

e.

Cannot be determined since it is a mixture.


13. Which of the following samples has the most molecules?

a.

1.00 L of CH4 at STP

b.

1.00 L of N2 at STP

c.

1.00 L of O2 at 20?C and 1.00 atm

d.

1.00 L of CO at 0.0?C and 1.25 atm

e.

1.00 L of C2H6 at -5.0?C and 0.75 atm


14. Which of the following statements is LEAST likely to be true of a sample of nitrogen gas?

a.

Molecules of gaseous nitrogen are in constant random motion.

b.

The pressure exerted by gaseous nitrogen is due to collisions of the molecules with the walls of the container.

c.

The average kinetic energy of the gaseous nitrogen is proportional to the absolute temperature of the gas.

d.

Collisions between the gaseous molecules are elastic.

e.

The volume of the sample would be zero at -273?C.


15. The molar volume of an ideal gas

a.

is decreased by increasing the temperature.

b.

always has a value of 22.4 L.

c.

is decreased by decreasing the pressure of the gas.

d.

is always lower than that of a real gas.

e.

is decreased by decreasing the kinetic energy of the gas molecules.

 

16.

The ratio of the number of molecules of sulfur dioxide to the number of oxygen in each of the containers shown above is

a.

1 : 1.

b.

1 : 2.

c.

2 : 1.

d.

3 : 2.

e.

641/2 : 32


17.

The molecules of the gases in the containers above have the same average

a.

speed.

b.

kinetic energy.

c.

molecular mass.

d.

molecular volume.

e.

van der Waals's gas constant a.


18. The behavior of HF(g) is most likely to approach the behavior of an ideal gas

a.

when the temperature is 0C and the pressure is one atmosphere.

b.

when the temperature is decreased and the pressure is increased.

c.

when the temperature is increased and the pressure is decreased.

d.

when both temperature and pressure are increased.

e.

when both temperature and pressure are decreased.

 


19. Under what set of conditions would H2S(g) be expected to have the best ideal behavior?

a.

High temperature and low pressure

b.

Low temperature and high pressure

c.

High temperature and high pressure

d.

Low temperature and low pressure

e.

Standard temperature and pressure

 


20. At a given temperature and pressure, which of the following gases would be expected to show the greatest deviation from the ideal gas law?

a.

NH3

b.

N2

c.

NO

d.

CH4

e.

O2

 

 

21. The ratio of the average rate of effusion of SO2(g) to CH4(g) at 300 K is

a.

1 : 4.

b.

1 : 2.

c.

4 : 1.

d.

2 : 1.

e.

641/2 : 161/2



 

 

 

 

 

 

22. The ratio of the average kinetic energies of O2 to CH4 at 298 K is

a.

2 to 1.

b.

1 to 1.

c.

1 to 2.

d.

321/2 to 161/2.

e.

161/2 to 321/2.

 


23. The ratio of the average speeds of O2 to CH4 at 298 K is

a.

2 to 1.

b.

1 to 1.

c.

1 to 2.

d.

321/2 to 161/2.

e.

161/2 to 321/2.

 


24. Five identical balloons are inflated to the same extent with the gases below. Which balloon could increase in size with time?

a.

CH4

b.

Ar

c.

He

d.

N2

e.

Ne

 


25. If 250 ml of methane, CH4, effuses through a small hole in 48 seconds, the time required for the same volume of helium to pass through the hole will be

a.

12 sec.

b.

24 sec.

c.

48 sec.

d.

96 sec.

e.

192 sec.