Thermodynamics Multiple Choice Questions & Answers (MCQs) on “Dalton’s Law of Partial Pressures and Gibbs Function”.
1. The expression which represents the pressure exerted by a gas is
a) nVRT
b) nRT/V
c) V/nRT
d) 1/nVRT
Answer: b
Clarification: This expression comes from the gas equation where V is the volume occupied by the gas at temperature T.
2. The expression nRT/V is called the partial pressure of a gas.
a) true
b) false
Answer: a
Clarification: This is the partial pressure that a gas exerts.
3. According to the Dalton’s law of partial pressures, the total pressure of a mixture of ideal gases is equal to the
a) difference of the highest and lowest pressure
b) product of the partial pressures
c) sum of the partial pressures
d) none of the mentioned
Answer: c
Clarification: According to the Dalton’s law of partial pressures, p=p1+p2+p3+…..+pc.
4. Which of the following relation is correct?
a) mole fraction of the Kth gas = moles of the Kth gas / total number of moles of gas
b) partial pressure of Kth gas = (mole fraction of the Kth gas)*(sum of the partial pressures)
c) sum of mole fractions of all the gases is unity
d) all of the mentioned
Answer: d
Clarification: All these statements come from the Dalton’s law of partial pressures.
5. The gas constant of the mixture is the ____ of the gas constants of the components.
a) average
b) weighted mean
c) sum
d) difference of the highest and the lowest
Answer: b
Clarification: It can be found from the Dalton’s law and gas equation.
6. A quantity called partial volume of a component of mixture is used.
a) true
b) false
Answer: a
Clarification: It is the volume which the component alone would occupy at the pressure and temperature of the mixture.
7. Which of the following statement is true?
a) V=V1+V2+….+Vc , where V is the partial volume of the component
b) 1/v = 1/(v1) + 1/(v2) + …….. + 1/(vc) , where v is the specific volume of the component
c) total density is equal to the sum of the densities of the components
d) all of the mentioned
Answer: d
Clarification: these relations come from the Dalton’s law and the gas equation.
8. The total entropy of a mixture of gases is the ____ of the partial entropies.
a) average
b) weighted mean
c) sum
d) difference of the highest and the lowest
Answer: c
Clarification: This is given by the Gibbs theorem.
9. When gases which are at equal pressure and temperature are mixed adiabatically without work, then
a) internal energy of the gaseous system remains constant
b) heat transfer of the gaseous system remains constant
c) entropy of the gaseous system remains constant
d) all of the mentioned
Answer: a
Clarification: This is because of the first law.
10. The fact that internal energy of a mixture is equal to the sum of the partial internal energies of the gases can also be applied to properties like H,Cv,Cp,S,F, and G.
a) true
b) false
Answer: a
Clarification: This statement comes from the Gibbs theorem.