A Carnot engine operating between temperatures T₁ and T₂ has efficiency 1/6. When T₂ is lowered by 62 K, its efficiency increases to 1/3. Then T₁ and T₂ are, respectively

• 372 K and 330 K

• 330 K and 268 K

• 310 K and 248 K

• 372 K and 310 K

A Carnot engine, having an efficiency of η = 1/10 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

• 99 J

• 90 J

• 1 J

• 100 J

B.

90 J

A Carnot engine, whose efficiency is 40%, takes in heat from a source maintained at a temperature of 500 K It is desired to have an engine of efficiency 60%. Then, the intake temperature for the same exhaust (sink) temperature must be

• the efficiency of Carnot engine cannot be made larger than 50%

• 1200 K

• 750 K 

• 600 K

A diatomic ideal gas is used in a Carnot engine as the working substance. If during the adiabatic expansion part of the cycle the volume of the gas increases from V to 32 V,the efficiency of the engine is

• 0.5

• 0.75

• 0.99

• 0.25

B.

0.75

A solid body of constant heat capacity 1 J/°C is being heated by keeping it in contact with reservoirs in two ways:
(i) Sequentially keeping in contact with 2 reservoirs such that each reservoir supplies the same amount of heat.
(ii) Sequentially keeping in contact with 8 reservoirs such that each reservoir supplies the same amount of heat. In both the cases body is brought from an initial temperature 100°C to final temperature 200°C. Entropy change of the body in the two cases respectively is:

• ln2,4ln2

• ln2,ln2

• ln2,2ln2

• 2ln2,8ln2