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GATE 2017 ME (ME2) – Question 55

Thermodynamics · Entropy changes, closed and open systems · 2 marks · Multiple choice

Air in a closed vessel occupies 2.87 m³ at 300 K. Gauge pressure is 0.5 bar, atmospheric pressure 1 bar and R = 287 J/kg K. Air mass is ______ kg.

  1. 1.67
  2. 3.33
  3. 5.00
  4. 6.66

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Show answer and explanation

Correct answer: (C) 5.00

Explanation

Use absolute pressure in pV=mRT: p=0.5+1=1.5bar=150000Pa. Then m=150000·2.87/(287·300)=**5kg, C**. Gauge pressure alone would give the incorrect1.67kg option.