11th class (Fsc) Physics unit 11 MCQs
51. Carnot cycle consists of:
a. Four steps
b. Two steps
c. Five steps
d. Three steps
52. A system does 600J of work and at the same time has its internal energy increased by 320J. How much heat has been supplied?
a. 600J
b. 280J
c. 200J
d. 920J
53. The efficiency of a Carnot Heat Engine is 100%. If temperature of sinkT2 is:
a. 0oF
b. 0oC
c. 100K
d. 0k
54. If heat engine absorbs 400 J and rejects 200 J heat energy, its efficiency will be:
a. 70%
b. 25%
c. 373oC
d. 50%
55. A heat engine operates between the temperature 1000K and 400K. its efficiency is:
a. 60%
b. 100%
c. 50%
d. 70%
56. The efficiency of heat engine whose sink is at 17oC and source at 200 is:
a. 80%
b. 38%
c. 90%
d. 65%
57. A carnot engine has an efficiency of 50% when its sink temperature is at 27oC. the temperature of source:
a. 327oC
b. 273oC
c. 373oC
d. 300oC
58. The Carnot cycle can be shown by which graph:
a. P-V graph
b. P-T graph
c. PV-T graph
d. V-T graph
59. Efficiency of a heat engine can be increased by:
a. Decreasing source temperature
b. Increasing sink temperature
c. Using ideal working substance
d. Decreasing sink temperature
60. If the temperature of sink is absolute zero then the efficiency of heat engine should be:
a. zero
b. 100%
c. infinite
d. 50%
61. The measures of hotness or coldness of a substance is:
a. Internal energy
b. Temperature
c. Energy
d. Heat
62. The temperature scale with is independent of nature of substance is:
a. Fahrenheit scale
b. Thermodynamics scale
c. Regnault scale
d. Centigrade scale
63. Value of Triple point of water is given as:
a. 273.16 K
b. zero K
c. 373.16K
d. 100 K
64. Unit of thermodynamics scale of temperature is:
a. Kelvin
b. Centigrade
c. Celsius
d. Fahrenheit
65. At which of the following temperature a body has maximum internal energy.
a. 273 K
b. -273
c. -273 K
d. 0 K
66. The triple point of water is:
a. 273.16K
b. Zero K
c. 6373.16K
d. 100k
67. Force acting on the piston to move outward is;
a. Power Stroke
b. Compressive Stroke
c. Exahaust Stroke
d. All Strokes
68. The actual efficiency of properly turned petrol engine is:
a. 40% to 45%
b. 20% to 305
c. 25% to 30%
d. 30% to 35%
69. No spark plug is needed in the:
a. Diesel engine
b. Petrol engine
c. Water engine
d. Gas engine
70. The number of spark plugs used in the diesel engine is equal to:
a. 2
b. 0
c. 3
d. 1
71. The efficiency of diesel engine is about:
a. 40% to 50%
b. 25% to 30%
c. 50% to 60%
d. 35% to 40%
72. Number of speak plugs needed in the diesel engine are:
a. 2
b. 0
c. 3
d. 1
73. The dimension of entropy are:
a. [ML2T2K-1]
b. [ML2T2]
c. [ML2T3]
d. [ML2T1K]
74. If heat is added to a system, then its entropy will:
a. Increase but negative
b. Increase and positive
c. Decrease but negative
d. Decrease and positive
75. When hot and cold water are mixed, the entropy?
a. Increases
b. Decreases
c. Zero
d. Remains constant
76. When temperature of source and sink of a heat engine becomes equal then the entropy changes will be:
a. Maximum
b. zero
c. Negative
d. Minimum
77. Efficiency of steam locomotive is:
a. 9%
b. 105
c. 7%
d. 8%
78. The change in entropy of a system is given by:
a. ΔQ = T/Δs
b. ΔS = ΔQ/T
c. ΔS = ΔQ x T
d. ΔQ = ΔS/T
79. Net change in entropy of a system after one complete carnot cycle is:
a. Zero
b. Positive
c. Sometime positive and sometime negative
d. Negative
80. Entropy is measure of:
a. Disorder of system
b. Internal energy of system
c. Potential energy of system
d. Order of system
81. The unit of entropy is:
a. J/K
b. Jk
c. K/J
d. K
82. Entropy remains constant in:
a. Isochoric process
b. Isothermal process
c. Isobaric process
d. Adiabatic process
83. The increase in thermal pollution of environment means:
a. Entropy remains constant
b. Increase in the entropy
c. Entropy becomes zero
d. Decrease in the entropy
84. Environmental crisis are also known as:
a. War crisis
b. Population crisis
c. Mass crisis
d. Entropy crisis
85. The entropy of the universe with passage of time is:
a. Remains constant
b. Increases
c. Increases & decreases
d. Deceases
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