This set of Physical Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Ideal Gases”.

1. The Internal energy of a real gas is a function of pressure as well as of temperature.

a) False

b) True

View Answer

Explanation: Pressure dependence results from forces between the molecules. If such forces did not exist, no energy would be required to alter the average intermolecular distance.

2. What is the relation between C_{P} and C_{V} for an ideal gas?

a) C_{P} = C_{V} + R

b) C_{V} = R

c) C_{P} = R

d) C_{P} + R = 0

View Answer

Explanation: C

_{P}= C

_{V}+ R is the relation between C

_{P}and C

_{V}for an ideal gas. This equation does not imply that C

_{P}and C

_{V}are themselves constant for an ideal gas, but only that they vary with temperature in such a way that their difference is equal to R.

3. What is the equation of an Isothermal process?

a) Q = -W = RT ln V_{2}/V_{1} = -RT ln P_{2}/P_{1}

b) Q = ΔH = ∫ C_{V} dT

c) ΔH = ∫ C_{V} dT

d) Q = ΔU = ∫ C_{V} dT

View Answer

Explanation: ΔU = ΔH = 0

And Q = RT ln V

_{2}/V

_{1}= -RT ln P

_{2}/P

_{1}

W = -RT ln V

_{2}/V

_{1}= RT ln P

_{2}/P

_{1}

Note that Q = -W. Therefore, Q = -W = RT ln V

_{2}/V

_{1}= -RT ln P

_{2}/P

_{1}

Proved.

4. What is the equation of Isobaric process?

a) Q = -W = RT ln V_{2}/V_{1} = -RT ln P_{2}/P_{1}

b) T_{2}/T_{1} = (V_{1}/V_{2})

c) C_{P} + R = 0

d) Q = ΔH = ∫ C_{P} dT

View Answer

Explanation: ΔU = ∫ C

_{V}dT

And ΔH = ∫ C

_{P}dT

W = -R (T

_{2}– T

_{1}) and Q = ∫ C

_{P}dT

Q = ΔH = ∫ C

_{P}dT

Proved.

5. What is partial molar property?

a) Pressure that species exert

b) Maintenance of temperature below that of surroundings

c) A process for the continuous conversion of heat into work

d) Equal to corresponding mole property as a pure species

View Answer

Explanation: A partial molar property (other than volume) of a constituent species in an ideal – gas mixture is equal to the corresponding molar property of the species as a pure ideal gas at the mixture temperature but at a pressure equal to its partial pressure in the mixture.

6. What is the volume of one mole of an ideal gas?

a) 22.710947

b) 33. 87584

c) 44. 97272

d) 55. 08487

View Answer

Explanation: The volume of one mole of an ideal gas is 22.710947(13) L at STP as defined by IUPAC since 1982.

7. At higher temperature and lower pressure gases behave as an ideal gas.

a) True

b) False

View Answer

Explanation: Potential energy due to the intermolecular forces become less significant. The size of the molecules also becomes less significant in comparison of empty space between them.

8. The expression for density is __________

a) PM/RT

b) PM = RT

c) 1/RT

d) PM = 0

View Answer

Explanation: PM/RT is an expression for density. At constant temperature and pressure, the density of the gas is directly proportional to the molar mass of the gas.

9. What is the volume of one mole of gas at ideal conditions?

a) 42.989 dm^{3}

b) 34.671 dm^{3}

c) 22.414 dm^{3}

d) 55.911 dm^{3}

View Answer

Explanation: The molar volume is the volume occupied by an ideal gas at STP. The molar volume of a gas at ideal conditions is 22.414 dm

^{3}at 0℃ and 24.465 dm

^{3}at 25℃.

10. 1 m^{3} is equal to?

a) 50 dm^{3}

b) 500 dm^{3}

c) 10 dm^{3}

d) 100 dm^{3}

View Answer

Explanation: Meter is the unit of length in International System of Units. The SI unit of meter is m. 1 m

^{3}is equal to 100 dm

^{3}.

**Sanfoundry Global Education & Learning Series – Physical Chemistry.**

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