Thermodynamics - Online Test

Q1. For solids near room temperature the molar specific heat (R is the universal gas constant)
Answer : Option B
Explaination / Solution:

The molar specific heats of solids also demonstrate a marked temperature dependence. Solids have molar specific heats that generally decrease in a nonlinear manner with decreasing temperature and approach zero as the temperature approaches absolute zero. At high temperatures (usually above 300 K), the molar specific heats approach the value of 3R ≈ 25 J/mol.K, a result known as the DuLong–Petit law.

Q2. If  and  are molar specific heat capacities of an ideal gas at constant pressure and volume respectively and R is the universal gas constant, relation between the three is
Answer : Option D
Explaination / Solution:

This is Meyer's Equation

At constant volume as there is no work done on the gas(ΔV=0) all the heat supplied goes for the increase of internal energy. Hence temperature of body increases with less supply of heat. Whereas at constant pressure heat supplied accounts for both internal energy and work done on the gas.

if we increase temp. of 1 mole of gas by 1K or 1C then


This is also called Meyer's formula.


Q3. In Thermodynamics Extensive variables depend
Answer : Option D
Explaination / Solution:

The variables which depend on the size or amount of the substance are called extensive variables. Example: Mass, volume etc

Q4. In case of isobaric process the volume of an ideal gas change the work done by the gas is given by
Answer : Option C
Explaination / Solution:



Q5. In a quasi-static process,
Answer : Option C
Explaination / Solution:

A quasi-static process is a thermodynamic process that happens slowly enough for the system to remain in internal equilibrium.

Q6. In which type of process is the volume constant
Answer : Option D
Explaination / Solution:

An isochoric process is a thermodynamic process during which the volume of the closed system undergoing such a process remains constant.

Q7. The heat engine takes
Answer : Option A
Explaination / Solution:

a heat engine converts heat energy to mechanical work by using the temperature difference between a hot "source" and a cold "sink". Heat is transferred from the source, through the "working body" of the engine, to the "sink", and in this process some of the heat changes into work by using the qualities of the gas or liquid inside the engine.

Q8. The efficiency (η) of a heat engine is defined by (W is the output and Q1 the heat input)
Answer : Option B
Explaination / Solution:

η=WorkDoneHeatInput=WQ1=Q1Q2Q1
Q9. A refrigerator's working substance
Answer : Option D
Explaination / Solution:
No Explaination.


Q10. The coefficient of performance K of a refrigerator is given by
Answer : Option D
Explaination / Solution:

The performance of refrigerator is expressed by means of cofficient of performance

cofficient of performance  = Heat extracted / work done =