KFUPM-Physics102-032

Dr.Aljalal

Sec07

Sec08

Sec09

Recitation ch 20

Answers at the end

Question 1

An ideal gas, initially occupies a volume of 0.380 m**3

at a pressure of 2.04*10**5 Pa, expands isothermally to

a pressure of 1.01*10**5 Pa.

Calculate the work done by the gas.

a 54.5 kJ

b 321 kJ

c 27.0 kJ

d 539 kJ

e 32.1 kJ

==============================================

Question 2

For an ideal gas, Which of the following statements are CORRECT:

1. Cp – Cv = R/2.

2. In an isothermal process, the internal energy of the

system does not change.

3. In an adiabatic process, no heat enters or leaves the system.

4. In a constant volume process, the work done by the system is

positive.

a 1, 2 and 4.

b 2 and 3.

c 3 and 4.

d 1 and 3.

e 2 and 4.

==============================================

Question 3

For a given temperature increase, a certain amount of

an ideal gas requires 80 J of heat when heated at

constant volume and 150 J of heat when heated at

constant pressure. How much work is done by the gas

in the second situation ?

a +70 J

b -80 J

c zero

d -70 J

e +80 J

==============================================

Question 4

Five moles, of an ideal monatomic gas, expand at constant

pressure of 1.0*10**2 Pascal from a volume of 1.0 m**3 to

to a volume of 3.0 m**3. What is the change in the internal

energy of the system?

a 300 J.

b 1000 J.

c 100 J.

d 600 J.

e 500 J.

==============================================

Question 5

An ideal gas occupies a volume of 12 L at 20 degrees-C

and a pressure of 1.0 atm. Its temperature is now raised

to 100 degrees-C and its pressure increases to 3.0 atm.

The new volume is:

a 25 L.

b 5.1 L.

c 0.20 L.

d 14 L.

e 21 L.

==============================================

Question 6

Two moles of helium (monatomic) gas are heated from 100

degrees Celsius to 250 degrees Celsius. How much heat is

transferred to the gas if the process is done at constant

pressure?

a 3.11 kJ.

b 8.52 kJ.

c 2.63 kJ.

d 1.51 kJ.

e 6.23 kJ.

==============================================

Question 7

An ideal gas containing 5.00 moles expands isothermally

at 127 degrees-C to four times its initial volume.

Find the heat flow during this expansion.

a 7.32 kJ out of the system

b 34.5 kJ out of the system

c 7.32 kJ into the system

d 23.0 kJ into the system

e 23.0 kJ out of the system

==============================================

Question 8

In an adiabatic process, the temperature of one mole of an

ideal monatomic gas is decreased from 500 K to 400 K.

What is the work done during the process in calories?

a 500

b 400

c 100

d 300

e 200

==============================================

Question 9

Two moles of a monatomic ideal gas is compressed at a constant

pressure of 1.5 atm from a volume of 70 liters to 35 liters.

Calculate the change in internal energy of the gas.

a - 0.87*10**4 J

b - 1.3*10**4 J

c - 1.9*10**4 J

d - 3.5*10**4 J

e 2.4*10**4 J

==============================================

Question 10

Which of the following statements is CORRECT ?

a For a given medium, the frequency of a wave is

inversely proportional to wavelength.

b The internal energy of an ideal gas depends on the

temperature and pressure only.

c A standing wave must be transverse.

d The rms speed of gas molecules decreases in

an isotherml process.

e Heat is a temperature difference.

==============================================

Question 11

An ideal gas undergoes an isothermal process starting with a

pressure of 2*10**5 Pa and a volume of 6 cm3. Which of the

following might be the pressure and volume of the final state?

a 6*10**5 Pa and 2 cm**3

b 4*10**5 Pa and 4 cm**3

c 8*10**5 Pa and 2 cm**3

d 1*10**5 Pa and 10 cm**3

e 3*10**5 Pa and 6 cm**3

==============================================

Question 12

One mole of an ideal monatomic gas is taken through

the cycle of figure 5.

Calculate the work done in a complete cycle.

a + 325 J

b - 525 J

c + 895 J

d zero

e + 623 J

==============================================

Question 13

One mole of an ideal monatomic gas is taken from A to C

along the diagonal path in figure 5. What is the change

in the internal energy of the gas in this process ?

a - 5.0 kJ

b ZERO

c - 3.0 kJ

d + 5.0 kJ

e + 3.0 kJ

==============================================

Question 14

Initially, an ideal monatomic gas containing 10.0 moles

occupies a volume of 30.0 L at a pressure of 5.00 atm.

It is then compressed adiabatically to a final volume of

12.0 L. What is the final temperature of the gas ?

a 844 K

b 457 K

c 157 K

d 420 K

e 336 K

==============================================

Question 15

One mole of an ideal monatomic gas is taken through the cyclic

process shown in the figure. Calculate the net heat (lost or

gained) by the gas during one complete cycle.

a 4*Po*Vo Joule (lost)

b 2*Po*Vo Joule (gained)

c 3*Po*Vo Joule (lost)

d 4*Po*Vo Joule (gained)

e 2*Po*Vo Joule (lost)

==============================================

Question 16

An ideal diatomic gas, initially at a pressure Pi = 1.0 atm

and volume Vi, is allowed to expand isothermally until it’s

volume doubles. The gas is then compressed adiabatically

until it reaches its original volume. The final pressure of

the gas will be:

a 1.3 atm.

b 0.5 atm.

c 1.7 atm.

d 2.0 atm.

e 0.4 atm.

==============================================

Question 17

Two moles of nitrogen are in a 3-liter container at a

pressure of 5.0*10**6 Pa. Find the average translational

kinetic energy of a molecule.

a 1.0*10**(-24) J.

b 1.1*10**(-23) J.

c 3.6*10**(-20) J.

d 1.9*10**(-20) J.

e 7.1*10**(-22) J.

==============================================

Question 18

The figure shows 5 paths traversed by a gas on a P-V diagram.

For which of the 5 paths is the change in internal energy

the greatest?

a 5

b 3

c 4

d 1 and 2

e 5 and 4

==============================================

Answers

1 a

2 b

3 a

4 a

5 b

6 e

7 d

8 d

9 b

10 a

11 a

12 e

13 c

14 e

15 c

16 a

17 d

18 a