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Set 9 of 17 · Questions 241-270 of 484

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JEE Main Physics · Thermodynamics · Set 9 (Q241-270)

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  1. 241.
    A steel ball of mass falls freely from a height of 20 and bounces to a height of from the ground. If the energy lost in this process is absorbed by the ball, the rise in its temperature is , specific heat capacity of steel is )
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  2. 242.
    A refrigerator works between and It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is (Take 1 Joules)
    1. (1)236.5
    2. (2)2365
    3. (3)2.365
    4. (4)23.65
  3. 243.
    A heating element of mass and having specific heat of is exposed to surrounding air at . The element attains a steady state temperature of while absorbing of electric power. if the power is switched Off, then approximate time taken by the element to cool down to will be (neglect radiation)
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  4. 244.
    1g of a liquid is converted to vapour at 3 x Pa pressure. If 10% of the heat supplied is used for increasing the volume by 1600 during this phase change, then the increase in internal energy in the process will be:
    1. (1)4320J
    2. (2)432000 J
    3. (3)4800 J
    4. (4)4.32 x J
  5. 245.
    The door of an operating refrigerator is kept open. As a result, the temperature of the room will
    1. (1)remain unchanged
    2. (2)increases
    3. (3)decreases
    4. (4)depends on the contents inside the refrigerator
  6. 246.
    If the door of a refrigerator is kept open then which of the following is ture
    1. (1)Room is cooled
    2. (2)Room is heated
    3. (3)Room is either cooled or heated
    4. (4)Room is neither cooled nor heated
  7. 247.
    The area of a circular copper coin increases by when its temperature is raised by . The coefficient of linear expansion of the coin is:
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  8. 248.
    An ideal gas heat engine operates in a Carnot's cycle between and . It absorbs 6 × 104 J at high temperature. The amount of heat converted into work is ....
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  9. 249.
    A thermodynamic process of uncontrolled change satisfying the equation , is heat supplied, work done]
    1. (1)cyclic
    2. (2)isothermal
    3. (3)isochroic
    4. (4)free expansion
  10. 250.
    When of water at is mixed with of water at . The resultant temperature is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  11. 251.
    We consider a thermodynamic system. If represents the increase in its internal energy and the work done by the system, which of the following statements is true?
    1. (1) in an isothermal process
    2. (2) in an isothermal process
    3. (3) in an adiabatic process
    4. (4) in an adiabatic process
  12. 252.
    In a cyclic process, work done by the system is
    1. (1)Zero
    2. (2)Equal to heat given to the system
    3. (3)More than the heat given to system
    4. (4)Independent of heat given to the system
  13. 253.
    A Carnot's engine used first an ideal monoatomic gas then an ideal diatomic gas. If the source and sink temperature are and respectively and the engine extracts 1000 J of heat in each cycle, then area enclosed by the PV diagram is
    1. (1)100 J
    2. (2)300 J
    3. (3)500 J
    4. (4)700 J
  14. 254.
    A metal cube absorbs of heat when its temperature is raised by . If the specific heat of the metal is , then the mass of the cube is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  15. 255.
    Consider a reversible engine of ecoefficiency . When the temperature of the sink is reduced by , its efficiency gets doubled, The temperature of the source and sink respectively are
    1. (1) and
    2. (2) and
    3. (3) and
    4. (4) and
  16. 256.
    An ideal gas at is compressed suddenly to of its initial volume. If for an ideal gas, then rise in its temperature is
    1. (1)
    2. (2)
    3. (3),
    4. (4)
  17. 257.
    A sample of 0.1 g of water at and normal pressure ( ) requires 54 cal of heat energy to convert to steam at . If the volume of the steam produced is 167.1 cc, the change in internal energy of the sample is [NEET 2018]
    1. (1)42.2 J
    2. (2)208.7 J
    3. (3)104.3 J
    4. (4)84.5 J
  18. 258.
    The coefficient of performance of refrigerator, whose efficiency is 25% is
    1. (1)1
    2. (2)3
    3. (3)5
    4. (4)7
  19. 259.
    An ideal gas in a cylinder is compressed adiabatically to one-third of its original volume. A work of is done on the gas by the process. The change in internal energy of the gas and the heat flowed into the gas, respectively are
    1. (1) and zero
    2. (2) and zero
    3. (3) and heat flows out of the gas
    4. (4) and heat flows into the gas
  20. 260.
    Two vessels separately contain two ideal gases and at the same temperature, the pressure of being twice that . Under such conditions, the density of is found to be 1.5 times the density . The ratio of molecular weight and is
    1. (1)2
    2. (2)
    3. (3)
    4. (4)
  21. 261.
    A metal cooking pot has a base area of and thickness . It boils water at a rate of when placed on a hot plate. The temperature of the part of the lot plate in contact with the pot is approximately [Thermalconductivity of metal is , heat of vaporisation of water is ]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  22. 262.
    The internal energy change in a system that has absorbed 2 kcal of heat and done 500 ofwork is
    1. (1)6400
    2. (2)5400
    3. (3)7900
    4. (4)8900
  23. 263.
    A hunter fired a metallic bullet of mass from a gun towards an obstacle and it just melts when it is stopped by the obstacle. The initial temperature of the bullet is . If th of heat is absorbed by the obstacle, then the minimum velocity of the bullet is (Melting point of bullet , Specific heat of bullet ,Latent heat of fusion of bullet )
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  24. 264.
    A calorimeter contains of water at . When of water at is added to it, the resulting temperature is found to be . The water equivalent of the calorimeter is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  25. 265.
    Work done by a Carnot engine operating between temperatures 127 °C and 27 °C is 2 kJ. The amount of heat transferred to the engine by the reservoir is:
    1. (1)8 kJ
    2. (2)2.67kJ
    3. (3)2 kJ
    4. (4)4 kJ
  26. 266.
    The heat energy released by water of mass when it is cooled by is (Specific heat capacity of water )
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  27. 267.
    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
    1. (1)5
    2. (2)8
    3. (3)6
    4. (4)6.5
  28. 268.
    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
    1. (1)200 K
    2. (2)400 K
    3. (3)600 K
    4. (4)800 K
  29. 269.
    A Carnot's engine operates with source at and sink at . If the source supplies of heat energy, the work done by the engine is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  30. 270.
    A monoatomic gas performs a work of where Q is the heat supplied to it. The molar heat capacity of the gas will be________R during this transformation. Where R is the gas constant.