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 |
 89%
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\(1~\text g\) of water of volume \(1~\text{cm}^3\) at \(100^\circ \text{C}\) is converted into steam at the same temperature under normal atmospheric pressure \(\approx 1\times10^{5}~\text{Pa}.\) The volume of steam formed equals \(1671~\text{cm}^3.\) If the specific latent heat of vaporization of water is \(2256~\text{J/g},\) the change in internal energy is:
1. \(2423~\text J\) 
2. \(2089~\text J\) 
3. \(167~\text J\) 
4. \(2256~\text J\) 

Subtopic:  First Law of Thermodynamics |
 67%
From NCERT
NEET - 2019
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Consider a cycle followed by an engine (figure). 


1 to 2 is isothermal,
2 to 3 is adiabatic,
3 to 1 is adiabatic.
Such a process does not exist, because:

(a) heat is completely converted to mechanical energy in such a process, which is not possible.
(b) In this process, mechanical energy is completely converted to heat, which is not possible.
(c) curves representing two adiabatic processes don’t intersect.
(d) curves representing an adiabatic process and an isothermal process don't intersect.

Choose the correct alternatives:

1. (a), (b) 2. (a), (c)
3. (b), (c) 4. (c), (d)
Subtopic:  First Law of Thermodynamics | Second Law of Thermodynamics |
 56%
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The figure below shows two paths that may be taken by gas to go from state \(A\) to state \(C.\) 
                    
In process \(AB,\) \(400~\text{J}\) of heat is added to the system, and in process \(BC,\)  \(100~\text{J}\) of heat is added to the system. The heat absorbed by the system in the process \(AC\) will be:
1. \(380~\text{J}\)
2. \(500~\text{J}\)
3. \(460~\text{J}\)
4. \(300~\text{J}\)

Subtopic:  First Law of Thermodynamics |
 59%
From NCERT
NEET - 2015
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The degree of freedom per molecule for a gas on average is 8. If the gas performs 100 J of work when it expands under constant pressure, then the amount of heat absorbed by the gas is:
1. 500 J
2. 600 J
3. 20 J
4. 400 J

Subtopic:  First Law of Thermodynamics |
 61%
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Heat is supplied to a diatomic gas in an isochoric process. The ratio \(\Delta Q:\Delta U\) is: (symbols have usual meanings)
1. \(5:3\)
2. \(5:2\)
3. \(1:1\)
4. \(5:7\)

Subtopic:  First Law of Thermodynamics |
 71%
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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 |
 81%
From NCERT
NEET - 2012
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A system is taken from state \(a\) to state \(c\) by two paths \(adc\) and \(abc\) as shown in the figure. The internal energy at \(a\) is \({U}_{a}=10~\text{J}.\) Along the path \(adc\) the amount of heat absorbed \(\delta Q_1=50~\text{J}\) and the work obtained \(\delta W_1=20~\text{J}\) whereas along the path \(abc\) the heat absorbed \(\delta Q_2 = 36~\text{J}.\) The amount of work along the path \(abc\) is: 
      
1. \(10~\text{J}\) 2. \(12~\text{J}\)
3. \(36~\text{J}\) 4. \(6~\text{J}\)
Subtopic:  First Law of Thermodynamics |
 81%
From NCERT
NEET - 2013
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A sample of \(0.1\) g of water at \(100^{\circ}\mathrm{C}\) and normal pressure (\(1.013 \times10^5\) N m–2) requires \(54\) cal of heat energy to convert it into steam at \(100^{\circ}\mathrm{C}\). If the volume of the steam produced is \(167.1\) cc, then the change in internal energy of the sample will be:
1. \(104.3\) J
2. \(208.7\) J
3. \(42.2\) J
4. \(84.5\) J

Subtopic:  First Law of Thermodynamics |
 70%
From NCERT
NEET - 2018
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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 |
 78%
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