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question_answer1)
A Carnot engine working between \[300\,K\] and 600K has work output of 800 J per cycle. What is amount of heat energy supplied to the engine from source per cycle [DPMT 1999; Pb. PMT 2002, 05; Kerala PMT 2004]
A)
1800 J/cycle done
clear
B)
1000 J/cycle done
clear
C)
2000 J/cycle done
clear
D)
1600 J/cycle done
clear
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question_answer2)
The coefficient of performance of a Carnot refrigerator working between \[{{30}^{o}}C\]and \[{{0}^{o}}C\] is [UPSEAT 2002]
A)
10 done
clear
B)
1 done
clear
C)
9 done
clear
D)
0 done
clear
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question_answer3)
If the door of a refrigerator is kept open, then which of the following is true [DPMT 2001; BHU 2001; JIPMER 2002; AIEEE 2002; CPMT 2003]
A)
Room is cooled done
clear
B)
Room is heated done
clear
C)
Room is either cooled or heated done
clear
D)
Room is neither cooled nor heated done
clear
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question_answer4)
In a cyclic process, the internal energy of the gas
A)
Increases done
clear
B)
Decreases done
clear
C)
Remains constant done
clear
D)
Becomes zero done
clear
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question_answer5)
Irreversible process is
A)
Adiabatic process done
clear
B)
Joule-Thomson expansion done
clear
C)
Ideal isothermal process done
clear
D)
None of the above done
clear
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question_answer6)
For a reversible process, necessary condition is
A)
In the whole cycle of the system, the loss of any type of heat energy should be zero done
clear
B)
That the process should be too fast done
clear
C)
That the process should be slow so that the working substance should remain in thermal and mechanical equilibrium with the surroundings done
clear
D)
The loss of energy should be zero and it should be quasistatic done
clear
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question_answer7)
In a cyclic process, work done by the system is [BHU 2002]
A)
Zero done
clear
B)
Equal to heat given to the system done
clear
C)
More than the heat given to system done
clear
D)
Independent of heat given to the system done
clear
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question_answer8)
An ideal gas heat engine operates in a Carnot's cycle between \[{{227}^{o}}C\] and \[{{127}^{o}}C\]. It absorbs 6 × 104 J at high temperature. The amount of heat converted into work is .... [KCET 2004]
A)
\[4.8\times {{10}^{4}}\,J\] done
clear
B)
\[3.5\times {{10}^{4}}\,J\] done
clear
C)
\[1.6\times {{10}^{4}}\,J\] done
clear
D)
\[1.2\times {{10}^{4}}\,J\] done
clear
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question_answer9)
An ideal heat engine exhausting heat at \[{{77}^{o}}C\] is to have a 30% efficiency. It must take heat at [BCECE 2004]
A)
\[{{127}^{o}}C\] done
clear
B)
\[{{227}^{o}}C\] done
clear
C)
\[{{327}^{o}}C\] done
clear
D)
\[{{673}^{o}}C\] done
clear
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question_answer10)
Efficiency of Carnot engine is 100% if [Pb. PET 2000]
A)
\[{{T}_{2}}=273\,\,K\] done
clear
B)
\[{{T}_{2}}=0\,\,K\] done
clear
C)
\[{{T}_{1}}=273\,\,K\] done
clear
D)
\[{{T}_{1}}=0\,\,K\] done
clear
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question_answer11)
A Carnot's engine used first an ideal monoatomic gas then an ideal diatomic gas. If the source and sink temperature are \[{{411}^{o}}C\] and \[{{69}^{o}}C\] respectively and the engine extracts 1000 J of heat in each cycle, then area enclosed by the PV diagram is [Pb. PET 2002]
A)
100 J done
clear
B)
300 J done
clear
C)
500 J done
clear
D)
700 J done
clear
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question_answer12)
A Carnot engine absorbs an amount Q of heat from a reservoir at an abosolute temperature T and rejects heat to a sink at a temperature of T/3. The amount of heat rejected is [UPSEAT 2004]
A)
Q / 4 done
clear
B)
Q / 3 done
clear
C)
Q / 2 done
clear
D)
2Q / 3 done
clear
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question_answer13)
The temperature of sink of Carnot engine is \[{{27}^{o}}C\]. Efficiency of engine is 25%. Then temperature of source is [DCE 2002; CPMT 2002]
A)
\[{{227}^{o}}C\] done
clear
B)
\[{{327}^{o}}C\] done
clear
C)
\[{{127}^{o}}C\] done
clear
D)
\[{{27}^{o}}C\] done
clear
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question_answer14)
The temperature of reservoir of Carnot's engine operating with an efficiency of 70% is 1000K. The temperature of its sink is [DCE 2003]
A)
300 K done
clear
B)
400 K done
clear
C)
500 K done
clear
D)
700 K done
clear
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question_answer15)
In a Carnot engine, when \[{{T}_{2}}={{0}^{o}}C\] and \[{{T}_{1}}={{200}^{o}}C,\] its efficiency is \[{{\eta }_{1}}\]and when \[{{T}_{1}}=0{{\,}^{o}}C\] and \[{{T}_{2}}=-200{{\,}^{o}}C\], Its efficiency is \[{{\eta }_{2}}\], then what is \[{{\eta }_{1}}/{{\eta }_{2}}\] [DCE 2004]
A)
0.577 done
clear
B)
0.733 done
clear
C)
0.638 done
clear
D)
Cannot be calculated done
clear
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question_answer16)
The efficiency of Carnot's engine operating between reservoirs, maintained at temperatures \[{{27}^{o}}C\] and \[-{{123}^{o}}C,\] is [DPMT 2002, 03; BVP 2004]
A)
50% done
clear
B)
24% done
clear
C)
0.75% done
clear
D)
0.4% done
clear
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question_answer17)
A Carnot engine operates between \[{{227}^{o}}C\] and \[{{27}^{o}}C.\] Efficiency of the engine will be [DCE 1999; BHU 2004]
A)
\[\frac{1}{3}\] done
clear
B)
\[\frac{2}{5}\] done
clear
C)
\[\frac{3}{4}\] done
clear
D)
\[\frac{3}{5}\] done
clear
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question_answer18)
A measure of the degree of disorder of a system is known as [Pb. PET 1997; MH CET 1999]
A)
Isobaric done
clear
B)
Isotropy done
clear
C)
Enthalpy done
clear
D)
Entropy done
clear
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question_answer19)
A carnot engine has the same efficiency between 800 K to 500 K and x K to 600 K. The value of x is [Pb. PMT 1996; CPMT 1996]
A)
1000 K done
clear
B)
960 K done
clear
C)
846 K done
clear
D)
754 K done
clear
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question_answer20)
A scientist says that the efficiency of his heat engine which operates at source temperature 127°C and sink temperature 27°C is 26%, then [CBSE PMT 2001]
A)
It is impossible done
clear
B)
It is possible but less probable done
clear
C)
It is quite probable done
clear
D)
Data are incomplete done
clear
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question_answer21)
A Carnot?s engine is made to work between 200°C and 0°C first and then between 0°C and ?200°C. The ratio of efficiencies of the engine in the two cases is [KCET 2002]
A)
1.73 : 1 done
clear
B)
1 : 1.73 done
clear
C)
1 : 1 done
clear
D)
1 : 2 done
clear
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question_answer22)
Efficiency of a Carnot engine is 50% when temperature of outlet is 500 K. In order to increase efficiency up to 60% keeping temperature of intake the same what is temperature of outlet [CBSE PMT 2002]
A)
200 K done
clear
B)
400 K done
clear
C)
600 K done
clear
D)
800 K done
clear
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question_answer23)
Even Carnot engine cannot give 100% efficiency because we cannot [AIEEE 2002]
A)
Prevent radiation done
clear
B)
Find ideal sources done
clear
C)
Reach absolute zero temperature done
clear
D)
Eliminate friction done
clear
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question_answer24)
?Heat cannot by itself flow from a body at lower temperature to a body at higher temperature? is a statement or consequence of [AIEEE 2003, EAMCET (Med.) 2003]
A)
Second law of thermodynamics done
clear
B)
Conservation of momentum done
clear
C)
Conservation of mass done
clear
D)
First law of thermodynamics done
clear
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question_answer25)
A Carnot engine takes \[3\times {{10}^{6}}\,cal\]. of heat from a reservoir at 627°C, and gives it to a sink at 27°C. The work done by the engine is [AIEEE 2003]
A)
\[4.2\times {{10}^{6}}J\] done
clear
B)
\[8.4\times {{10}^{6}}J\] done
clear
C)
\[16.8\times {{10}^{6}}J\] done
clear
D)
Zero done
clear
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question_answer26)
The first operation involved in a Carnot cycle is [AFMC 1998]
A)
Isothermal expansion done
clear
B)
Adiabatic expansion done
clear
C)
Isothermal compression done
clear
D)
Adiabatic compression done
clear
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question_answer27)
For which combination of working temperatures the efficiency of Carnot?s engine is highest [KCET 2000]
A)
80 K, 60 K done
clear
B)
100 K, 80 K done
clear
C)
60 K, 40 K done
clear
D)
40 K, 20 K done
clear
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question_answer28)
The efficiency of Carnot engine when source temperature is T1 and sink temperature is T2 will be [DCE 2000]
A)
\[\frac{{{T}_{1}}-{{T}_{2}}}{{{T}_{1}}}\] done
clear
B)
\[\frac{{{T}_{2}}-{{T}_{1}}}{{{T}_{2}}}\] done
clear
C)
\[\frac{{{T}_{1}}-{{T}_{2}}}{{{T}_{2}}}\] done
clear
D)
\[\frac{{{T}_{1}}}{{{T}_{2}}}\] done
clear
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question_answer29)
An ideal heat engine working between temperature T1 and T2 has an efficiency h, the new efficiency if both the source and sink temperature are doubled, will be [DPMT 2000]
A)
\[\frac{\eta }{2}\] done
clear
B)
\[\eta \] done
clear
C)
\[2\eta \] done
clear
D)
\[3\eta \] done
clear
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question_answer30)
An ideal refrigerator has a freezer at a temperature of \[-13{}^\circ C.\] The coefficient of performance of the engine is 5. The temperature of the air (to which heat is rejected) will be [BHU 2000; CPMT 2002]
A)
325°C done
clear
B)
325K done
clear
C)
39°C done
clear
D)
320°C done
clear
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question_answer31)
In a mechanical refrigerator, the low temperature coils are at a temperature of ? 23°C and the compressed gas in the condenser has a temperature of 27°C. The theoretical coefficient of performance is [UPSEAT 2001]
A)
5 done
clear
B)
8 done
clear
C)
6 done
clear
D)
6.5 done
clear
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question_answer32)
An engine is supposed to operate between two reservoirs at temperature 727°C and 227°C. The maximum possible efficiency of such an engine is [UPSEAT 2005]
A)
1/2 done
clear
B)
1/4 done
clear
C)
3/4 done
clear
D)
1 done
clear
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question_answer33)
An ideal gas heat engine operates in Carnot cycle between 227°C and 127°C. It absorbs \[6\times {{10}^{4}}\] cals of heat at higher temperature. Amount of heat converted to work is [CBSE PMT 2005]
A)
\[2.4\times {{10}^{4}}\]cal done
clear
B)
\[6\times {{10}^{4}}\] cal done
clear
C)
\[1.2\times {{10}^{4}}\] cal done
clear
D)
\[4.8\times {{10}^{4}}\] cal done
clear
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question_answer34)
Which of the following processes is reversible [CBSE PMT 2005]
A)
Transfer of heat by radiation done
clear
B)
Electrical heating of a nichrome wire done
clear
C)
Transfer of heat by conduction done
clear
D)
Isothermal compression done
clear
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