GATE Objective Questions Thermodynamics

Thermodynamics : Objective Questions

1. Which of the following is the extensive property of a thermodynamic system?

A. Pressure

B. Density

C. Volume

D. Temperature

View Answer/Explanation

Correct Answer is C

Properties whose values depend on the mass of a system like – Volume etc.

2. In which one of the following working substances, does the relation T1 /T2 = (ρ1 2)0.286 hold if the process takes place with zero heat transfer?

A. Wet Steam

B. Air

C. Isentropic

D. Petrol Vapor and Air mixture

View Answer/Explanation

Correct Answer is B

Air

T1 /T2 = (ρ1 2)(γ-1)/γ

Put γ = 1.4

3. In new temperature scale say °D, the boiling and freezing points of water at one atmosphere are 100 °D and 300 °D respectively. Correlate the scale with the Centigrade scale. The reading of 0 °D on the Centigrade scale is-

A. 0 °C

B. 25 °C

C. 100 °C

D. 150 °C

View Answer/Explanation

Correct Answer is D

150 °C

Use the basic formula, used for conversion.

4. Which of the following statements applicable to a perfect gas will also be true for an irreversible process?

A. Tds = du + pdV

B. dQ = du + pdV

C. dQ = Tds

D. None of these

View Answer/Explanation

Correct Answer is A

Tds = du +pdV

All these are properties.

5. The correct sequence in decreasing order of the value of characteristic gas constant of the given gases –

A. Nitrogen, Air, Hydrogen, Carbon-di-oxide

B. Nitrogen, Air, Carbon-di-oxide, Hydrogen,

C. Air, Nitrogen, Hydrogen, Carbon-di-oxide

D. Hydrogen, Nitrogen, Air, Carbon-di-oxide

View Answer/Explanation

Correct Answer is D

Characteristic Gas Constant is inversely proportional to Molecular Weight.

So,

Hydrogen = 2

Nitrogen = 28

Air = 29

CO2 = 44

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