If the door of a refrigerator is kept open, then which of the following is true ?

1. Room is cooled

2. Room is heated

3. Room is either cooled or heated

4. Room is neither cooled nor heated

Concept Questions :-

Heat engine and refrigerator
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In a cyclic process, the internal energy of the gas -

(1) Increases

(2) Decreases

(3) Remains constant

(4) Becomes zero

Concept Questions :-

Cyclic process
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

For a reversible process, necessary condition is -

(1) In the whole cycle of the system, the loss of any type of heat energy should be zero

(2) That the process should be too fast

(3) That the process should be slow so that the working substance should remain in thermal and mechanical equilibrium with the surroundings

(4) The loss of energy should be zero and it should be quasistatic

Concept Questions :-

Types of processes
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A Carnot's engine used first an ideal monoatomic gas then an ideal diatomic gas. If the source and sink temperature are 411°C and 69°C respectively and the engine extracts 1000 J of heat in each cycle, then area enclosed by the PV diagram is -

(1) 100 J

(2) 300 J

(3) 500 J

(4) 700 J

Concept Questions :-

Heat engine and refrigerator
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The temperature of sink of Carnot engine is 27°C. Efficiency of engine is 25%. Then temperature of source is -

(1) 227°C

(2) 327°C

(3) 127°C

(4) 27°C

Concept Questions :-

Heat engine and refrigerator
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The temperature of reservoir of Carnot's engine operating with an efficiency of 70% is 1000K. The temperature of its sink is -

(1) 300 K

(2) 400 K

(3) 500 K

(4) 700 K

Concept Questions :-

Heat engine and refrigerator
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In a Carnot engine, when T2 = 0°C and T1 = 200°C, its efficiency is η1 and when T1 = 0°C and T2 = –200°C, its efficiency is ${\eta }_{2}$, then what is η1 /η2 ?

(1) 0.577

(2) 0.733

(3) 0.638

(4) Can not be calculated

Concept Questions :-

Heat engine and refrigerator
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The efficiency of Carnot's engine operating between reservoirs, maintained at temperatures 27°C and –123°C, is

(1) 50%

(2) 24%

(3) 0.75%

(4) 0.4%

Concept Questions :-

Heat engine and refrigerator
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A Carnot engine operates between 227°C and 27°C . Efficiency of the engine will be -

(1) $\frac{1}{3}$

(2) $\frac{2}{5}$

(3) $\frac{3}{4}$

(4) $\frac{3}{5}$

Concept Questions :-

Heat engine and refrigerator
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

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) 200 K

(2) 400 K

(3) 600 K

(4) 800 K

Concept Questions :-

Heat engine and refrigerator