An ideal gas expands isothermally from  at 300 K against a constant pressure of . The work done by  the gas is:

 1 +270 kJ 2 –900 J 3 +900 kJ 4 –900 kJ
Subtopic:  First Law of Thermodynamics |
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NEET - 2019
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When 1 mol gas is heated at constant volume, the temperature is raised from 298 to 308 K. Heat supplied to the gas is 500 J. The correct statement among the following is:
1.  q = w = 500 J, ∆U = 0
2.  q = ∆U = 500 J, w = 0
3.  q = w = 500 J, ∆U = 0
4.  ∆U = 0, q = w = – 500 J

Subtopic:  First Law of Thermodynamics |
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AIPMT - 2001
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The work done when 1 mole of gas expands reversibly and isothermally from a pressure of 5 atm to 1 atm at 300 K is: ​
(Given log 5 = 0.6989 and R = 8.314 J K-1 mol-1)
1. zero J
2. 150 J
3. +4014.6 J
4. -4014.6 J

Subtopic:  First Law of Thermodynamics |
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NEET - 2022
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When 1 g H2 gas at S.T.P is expanded to twice its initial volume, then the work done is:

1. 22.4 L atm
2. 5.6 L atm
3. 11.2 L atm
4. 44.8 L atm

Subtopic:  First Law of Thermodynamics |
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Two litres of an ideal gas at a pressure of 10 atm expands isothermally at 25 °C into a vacuum until its total volume is 10 litres. The amount of heat absorbed during expansion is:

1. 80 J

2. -80 J

3. Zero

4. 50 J

Subtopic:  First Law of Thermodynamics |
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Match the item in column I and in column II.

 Column I Column II a. No heat is absorbed by the system from the surroundings, but work (w) is done on the system. i. ∆U = q – w, closed system. b. No work is done on the system, but q amount of heat is taken out from the system and given to the surroundings. ii. ∆U = wad, a wall is adiabatic. c. w amount of work is done by the system and q amount of heat is supplied to the system. iii. ∆U  = –q, thermally conducting walls.

 1 a = i; b = ii; c = iii 2 a = ii; b = i; c = iii 3 a = ii; b = iii; c = i 4 a = iii; b = ii; c = i
Subtopic:  First Law of Thermodynamics |
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