# Thermodynamics Questions and Answers – Equations of State of a Gas

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This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Equations of State of a Gas”.

1. A mole of a substance has a mass equal to the molecular weight of the substance.
a) true
b) false

Explanation: 1gm of oxygen has mass of 32gm and 1gm of nitrogen has a mass of 28gm and so on.

2. According to Avogadro’s law, volume of a g mol of all gases at the pressure of ____ and temperature of ____ is same.
a) 760 mm Hg, 100 degree Celsius
b) 760 mm Hg, 0 degree Celsius
c) 750 mm Hg, 100 degree Celsius
d) 750 mm Hg, 0 degree Celsius

Explanation: This is the Avogadro law and these temperature and pressure condition is know as normal temperature and pressure(NTP).

3. At NTP, the volume of a g mol of all gases is(in litres)
a) 22.1
b) 22.2
c) 22.3
d) 22.4

Explanation: This comes from the Avogadro’s law.
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4. Which of the following statement is true?
a) number of kg moles of a gas = mass / molecular weight
b) molar volume = total volume of the gas / number of kg moles
c) both of the mentioned
d) none of the mentioned

Explanation: Number of moles is in kgmoles and molar volume is in (m^3)/kg mol.

5. The equation of state is a functional relationship between
a) pressure
b) molar or specific volume
c) temperature
d) all of the mentioned

Explanation: It is expressed in the form f(p,v,T)=0.

6. If two properties (out of p,v,T) of a gas are known, the third can be evaluated.
a) true
b) false

Explanation: The third property can be calculated from the equation of state.

7. Which of the following statement is true about a gas?
a) lim(pv) with p tending to 0 is independent of the nature of gas
b) lim(pv) with p tending to 0 depends only on the temperature
c) this holds true for all the gases
d) all of the mentioned

Explanation: This is one of the fundamental property for all the gases.

8. Universal gas constant is given by
a) lim(pv) / 273.16
b) R
c) 0.083 litre-atm/gmol K
d) all of the mentioned

Explanation: Putting the value of lim(pv) = 22.4 litre-atm/gmol we get the value of R.

9. The equation of state of a gas is lim(pv)=RT .
a) true
b) false

Explanation: The limit is calculated with p tending to 0 and v is the molar volume here.

10. For which of the following gases, does the product (pv) when plotted against p gives depends only on temperature?
a) nitrogen
b) hydrogen
c) air and oxygen
d) all of the mentioned

Explanation: It is a fundamental property of gas that lim(pv) with p tending to 0 is independent of the nature of gas and depends only on the temperature.

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