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Set 6 of 17 · Questions 151-180 of 484

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JEE Main Physics · Thermodynamics · Set 6 (Q151-180)

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  1. 151.
    A mass of diatomic gas at a pressure of 2 atmospheres is compressed adiabatically so that its temperature rises from to . The pressure ofthe gas in the final state is
    1. (1)8 atm
    2. (2)28 atm
    3. (3)68.7 atm
    4. (4)256 atm
  2. 152.
    A Carnot engine (E) is working between two temperatures 473 K and 273 K. In a new system two engines-engine works between 473 K to 373 K and engine E2 works between 373 K to 273 K. If and are the efficiencies of the engines and E2, respectively, then
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  3. 153.
    of water at is added to of water at . Neglecting heat capacity of vessel and other losses, then resultant temperature will be nearly
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  4. 154.
    A hole of diameter is drilled in a metal sheet at . The linear expansion of metal is . The diameter of the hole when the temperature is raised to , is equal to
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  5. 155.
    A Carnot engine takes heat from a reservoir at and rejects heat to a sink at . Its efficiency will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  6. 156.
    The work of 146 kJ is performed in order to compress one kilo mole of a gas adiabatically and in this process the temperature of the gas increases by 7. The gas is (R = 8.3 J )
    1. (1)diatomic
    2. (2)triatomic
    3. (3)mixture of monoatomic and diatomic
    4. (4)monoatomic
  7. 157.
    A work of is done to adiabatically compress one mole of a gas. If the increase in the temperature of the gas is , the gas is
    1. (1)monatomic
    2. (2)diatomic
    3. (3)polyatomic
    4. (4)mixture of diatomic and polyatomic
  8. 158.
    For a certain gas the ratio of specific heats is given to be . For this gas
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  9. 159.
    The temperature of a body is increased from to . The ambient temperature is . The energies emitted per second by the body at and are and respectively. The ratio of is
    1. (1)1.8
    2. (2)2.7
    3. (3)3.1
    4. (4)4.3
  10. 160.
    Cascaded Carnot engine is an arrangement in which heat sink of one engine is source for other. If high temperature for one engine is , low temperature for other engine is (Assume work done by both engine is same) Calculate lower temperature of first engine.
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  11. 161.
    An engine has an efficiency of 0.25 when temperature of sink is reduced by 58°C, if its efficiency is doubled, then the temperature of the source is
    1. (1)150°C
    2. (2)222°C
    3. (3)242°C
    4. (4)232°C
  12. 162.
    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
    1. (1)1/2
    2. (2)¼
    3. (3)3/4
    4. (4)1
  13. 163.
    In a Carnot's engine, as the gas absorbs heat energy from the source, then the temperature of the source
    1. (1)decreases
    2. (2)increases
    3. (3)remains constant
    4. (4)becomes zero
  14. 164.
    A sample of gas at temperature is adiabatically expanded to double its volume. Adiabatic constant for the gas is . The work done by the gas in the process is: mole
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  15. 165.
    In a cyclic process, the internal energy of the gas
    1. (1)Increases
    2. (2)Decreases
    3. (3)Remains constant
    4. (4)Becomes zero
  16. 166.
    Let is the efficiency of an engine at T1 = 447°C and T2 = 147°C while is the efficiency at T1 = 947°C and T2 = 47°C. The ratio will be:
    1. (1)0.41
    2. (2)0.56
    3. (3)0.73
    4. (4)0.70
  17. 167.
    The efficiency of Carnot's engine operating between reservoirs, maintained at temperatures 27° C and –123° C, is
    1. (1)50%
    2. (2)24%
    3. (3)0.75%
    4. (4)0.4%
  18. 168.
    A Carnot engine works between 600 K and 300 K. In each cycle of operations, the engine draws 1000joule of energy from the source at 600 K. The efficiency of the engine is –
    1. (1)20%
    2. (2)50%
    3. (3)70%
    4. (4)90%
  19. 169.
    176 grams of can change its temperature from to by absorbing 3600 joules of thermal energy. Molar specific heat of in is
    1. (1)30
    2. (2)40
    3. (3)50
    4. (4)60
  20. 170.
    The efficiency of Carnot's engine operating between reservoirs, maintained at temperatures and is
    1. (1)50%
    2. (2)24%
    3. (3)0.75%
    4. (4)0.4%
  21. 171.
    When the absolute temperature of the source of a Carnot heat engine is increased by , its efficiency increases by . The new efficiency of the engine is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  22. 172.
    The ratio of the specific heats in terms of degrees of freedom (n) is given by
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  23. 173.
    2 moles of a monatomic gas requires heat energy to be heated from to at constant volume. The heat energy required to raise the temperature of 4 moles of a diatomic gas from to at constant volume is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  24. 174.
    A Cannot engine works between 200ºC and 0ºC. Another Carnot engine works between 0ºC and –200ºC. In both cases the working substance absorbs 4 kilocalories of heat from the source. The efficiency of first engine will be –
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  25. 175.
    Consider a two stage Carnot engine. In the first stage heat is absorbed at temperature and heat is expelled at temperature (where ). In the second stage heat is absorbed at temperature and heat is expelled at temperature . The efficiency of the Carnot engine will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  26. 176.
    is the specific heat ratio of monoatomic gas A having 3 translational degrees of freedom. is the specific heat ratio of polyatomic gas having 3 translational, 3 rotational degrees of freedom and 1 vibrational mode. If , then the value of is ____ .
  27. 177.
    A wire of length 10 cm and diameter 0.5 mm is used in a bulb. The temperature of the wire is and power radiated by the wire is 94.2 W. Its emissivity is where _______ .
    (Given and assume that the emissivity of wire material is same at all wavelength.)
  28. 178.
    An ideal gas initially at temperature, is compressed suddenly to one fourth of its volume. If the ratio of specific heat at constant pressure to that at constant volume is , the change in temperature due to the thermodynamic process is K.
  29. 179.
    A container of fixed volume contains a gas at . To double the pressure of the gas, the temperature of gas should be raised to .
  30. 180.
    The temperature of 3.00 mol of an ideal diatomic gas is increased by 40.00C without changing the pressure of the gas. The molecules in the gas rotate but do not oscillate. If the ratio of change in internal energy of the gas to the amount of workdone by the gas is . Then the value of x (round off to the nearest integer) is .... (Given )