The first law of thermodynamics is based on:

 1 the concept of temperature. 2 the concept of conservation of energy. 3 the concept of working of heat engine. 4 the concept of entropy.

Subtopic:  First Law of Thermodynamics |
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When a system is moved from state a to state b along the path acb, it is discovered that the system absorbs 200 J of heat and performs 80 J of work.  Along the path adb, heat absorbed Q = 144 J. The work done along the path adb is:

 1 6 J 2 12 J 3 18 J 4 24 J
Subtopic:  First Law of Thermodynamics |
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Two cylinders, $$A$$ and $$B$$, of equal capacity are connected to each other via a stopcock. $$A$$ contains gas at a standard temperature and pressure. $$B$$ is completely evacuated. The entire system is thermally insulated. If the stopcock is suddenly opened, then the change in internal energy of the gas is:
1. $$0$$
2. $$5~\text{J}$$
3. $$1~\text{J}$$
4. $$3~\text{J}$$
Subtopic:  First Law of Thermodynamics |
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We consider a thermodynamic system. If $$\Delta U$$ represents the increase in its internal energy and $$W$$ the work done by the system, which of the following statements is true?
 1 $$\Delta {U}=-{W}$$ in an isothermal process. 2 $$\Delta {U}={W}$$ in an isothermal process. 3 $$\Delta {U}=-{W}$$ in an adiabatic process. 4 $$\Delta {U}={W}$$ in an adiabatic process.
Subtopic:  First Law of Thermodynamics |
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AIPMT - 1998
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The latent heat of vaporisation of water is $$2240~\text{J/gm}$$. If the work done in the process of expansion of $$1~\text{g}$$ is $$168~\text{J}$$, then the increase in internal energy is:
1. $$2408~\text{J}$$
2. $$2240~\text{J}$$
3. $$2072~\text{J}$$
4. $$1904~\text{J}$$

Subtopic:  First Law of Thermodynamics |
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An ideal gas goes from state $$A$$ to state $$B$$ via three different processes, as indicated in the $$P\text-V$$ diagram. If $$Q_1,Q_2,Q_3$$${}_{}$ indicates the heat absorbed by the gas along the three processes and $$\Delta U_1, \Delta U_2, \Delta U_3$$ indicates the change in internal energy along the three processes respectively, then:

 1 $${Q}_1>{Q}_2>{Q}_3$$ and $$\Delta {U}_1=\Delta {U}_2=\Delta {U}_3$$ 2 $${Q}_3>{Q}_2>{Q}_1$$  and $$\Delta {U}_1=\Delta {U}_2=\Delta {U}_3$$ 3 $${Q}_1={Q}_2={Q}_3$$ and $$\Delta {U}_1>\Delta {U}_2>\Delta {U}_3$$ 4 $${Q}_3>{Q}_2>{Q}_1$$ and $$\Delta {U}_1>\Delta {U}_2>\Delta {U}_3$$
Subtopic:  First Law of Thermodynamics |
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NEET - 2012
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A system is taken from state A to state B along two different paths, 1 and 2. If the heat absorbed and work done by the system along these two paths are ${Q}_{1},$ ${Q}_{2}$ $and$ ${W}_{1},$ ${W}_{2}$ respectively, then:

 1 $$Q_1=Q_2$$ 2 $$W_1=W_2$$ 3 $$Q_1-W_1=Q_2-W_2$$ 4 $$Q_1+W_1=Q_2+W_2$$
Subtopic:  First Law of Thermodynamics |
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An ideal monoatomic gas $$\left(\gamma = \frac{5}{3}\right )$$ absorbs 50 cal in an isochoric process. The increase in internal energy of the gas is:

 1 20 cal 2 Zero 3 50 cal 4 30 cal
Subtopic:  First Law of Thermodynamics |
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1 kg of gas does 20 kJ of work and receives 16 kJ of heat when it is expanded between two states. The second kind of expansion can be found between the same initial and final states, which requires a heat input of 9 kJ. The work done by the gas in the second expansion will be:

 1 32 kJ 2 5 kJ 3 -4 kJ 4 13 kJ
Subtopic:  First Law of Thermodynamics |
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If a gas undergoes the change in its thermodynamic state from A to B via two different paths, as shown in the given pressure (P) versus volume (V) graph, then:

 1 the temperature of the gas decreases in path 1 from A to B. 2 the heat absorbed by the gas in path 1 is greater than in path 2. 3 the heat absorbed by the gas in path 2 is greater than in path 1. 4 the change in internal energy in path 1 is greater than in path 2.

Subtopic:  First Law of Thermodynamics |
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