JEE Advanced (Assertion-Reason Type): Heat & Thermodynamics | Chapter-wise Tests for JEE Main & Advanced PDF Download

Directions: Each of these questions contain two statements, Assertion and Reason. Each of these questions also has alternative choices, only one of which is the correct answer.
Q.1.  Assertion : When a bottle of cold carbonated drink is opened, a slight fog forms around the opening.
Reason : Adiabatic expansion of the gas causes lowering of temperature and condensation of water vapours.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.

Correct Answer is option (a)
When a bottle of cold carbonated drink is opened. A slight fog forms around the opening. This is because of adiabatic expansion of gas causes lowering of temperature and condensation of water vapours.

Q.2. Assertion : In adiabatic compression, the internal energy and temperature of the system get decreased.
Reason : The adiabatic compression is a slow process
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.

Correct Answer is option (d)
Adiabatic compression is a rapid action and both the internal energy and the temperature increases.

Q.3. Assertion : We can not change the temperature of a body without giving (or taking) heat to (or from) it.
Reason : According to principle of conservation of energy, total energy of a system should remains conserved.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.

Correct Answer is option (d)
We can change the temperature of a body without giving (or taking) heat to (or from) it. For example in an adiabatic compression temperature rises and in an adiabatic expansion temperature false, although no heat is given or taken from the system in the respective changes.

Q.4. Assertion : Reversible systems are difficult to find in real world.
Reason : Most processes are dissipative in nature
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.

Correct Answer is option (a)
In a perfectly reversible system, there is no loss of energy. Losses can be minimised, friction can be reduced, the resistance in L-C oscillating system can also be negligible. But one cannot completely eliminate energy losses. This makes a perfectly reversible system, an ideal.

Q.5. Assertion : Thermodynamic process in nature are irreversible.
Reason : Dissipative effects can not be eliminated.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.

Correct Answer is option (a)
In reversible process, there always occurs some loss of energy. This is because energy spent in working against the dissipative force is not recovered back. Some irreversible process occur in nature such as friction where extra work to cancel the effect of friction. Salt dissolves in water but a salt does not separate by itself into pure salt and pure water.

Q.6. Assertion : Work and heat are two equivalent form of energy.
Reason : Work is the transfer of mechanical energy irrespective of temperature difference, whereas heat is the transfer of thermal energy because of temperature difference only.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.

Correct Answer is option (a)
Heat is similar to work in that both represent ways of transferring energy. Neither heat nor work is an intrinsic property of a system, that is, we cannot say that a system contains a certain amount of heat or work.

Q.7.  Assertion: Reversible systems are difficult to find in real world.
Reason: Most processes are dissipative in nature.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (a)
In a perfectly reversible system, there is no loss of energy. Losses can be minimised, friction can be reduced, the resistance in L-C oscillating system can also be negligible. But one cannot completely eliminate energy losses. This makes a perfectly reversible system, an ideal.

Q.8. Assertion: Air quickly leaking out of a balloon becomes coolers
Reason: The leaking air undergoes adiabatic expansion.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (a)
Adiabatic expansion produces cooling.

Q.9. Assertion: Thermodynamic process in nature are irreversible.
Reason: Dissipative effects can not be eliminated.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (a)
In reversible process, there always occurs some loss of energy. This is because energy spent in working against the dissipative force is not recovered back. Some irreversible process occur in nature such as friction where extra work to cancel the effect of friction. Salt dissolves in water but a salt does not separate by itself into pure salt and pure water.

Q.10. Assertion: The isothermal curves intersect each other at a certain point.
Reason: The isothermal change takes place slowly, so the isothermal curves have very little slope.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (e)
As isothermal processes are very slow and so the different isothermal curves have different slopes so they cannot intersect each other.

Q.11. Assertion: In adiabatic compression, the internal energy and temperature of the system get decreased.
Reason: The adiabatic compression is a slow process
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (d)
Adiabatic compression is a rapid action and both the internal energy and the temperature increases.

Q.12. Assertion: In isothermal process whole of the heat energy supplied to the body is converted into internal energy.
Reason: According to the first law of thermodynamics ΔQ = ΔU + pΔV.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (e)
As there is no change in internal energy of the system during an isothermal change. Hence, the energy taken by the gas is utilised by doing work against external pressure. According to FLOT ΔQ =  ΔU + PΔV Hence ΔQ = ΔU = PΔV Therefore, reason is true and assertion is false.

Q.13. Assertion: Zeroth law of thermodynamic explain the concept of energy.
Reason: Energy is dependent on temperature.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (e)
Zeroth law of thermodynamics explain the concept of temperature. According to which there exist a scalar quantity called temperature which is property of all thermodynamic system.

Q.14. Assertion: First law of thermodynamics is a restatement of the principle of conservation
Reason: Energy is fundamental quantity.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (c) 
First law of thermodynamics is restatement of the principal of conservation of energy as applied to heat energy.

Q.15. Assertion: In an adiabatic process, change in internal energy of a gas is equal to work done on or by the gas in the process.
Reason: Temperature of gas remains constant in a adiabatic process.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (c) 
In an adiabatic process, no exchange of heat is permissible i.e., ΔQ = 0. As, ΔQ = ΔU + ΔW = 0 ⇒ ΔU = −ΔW. Also in adiabatic process, temperature of gas changes.

Q.16. Assertion: The internal energy of an isothermal process does not change.
Reason: The internal energy of a system depends only on pressure of the system.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (c) 
The internal energy of system depends only on its temperature. In isothermal process temperature does not change, therefore, internal energy of the system remains the same.

Q.17. Assertion: If an electric fan be switched on in a closed room, the air of the room will be cooled.
Reason: Fan air decrease the temperature of the room.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (d)
If an electric fan is switched on in a closed room, the air will be heated because due to motion of the fan, the speed of air molecules will increase. In fact, we feel cold due to evaporation of our sweat.

Q.18. Assertion: A room can be cooled by opening the door of a refrigerator in a closed room. Reason: Heat flows from lower temperature (refrigerator) to higher temperature (room).
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (d)
When the door of refrigerator is kept open, heat rejected by the refrigerator to the room will be more than the heat taken by the refrigerator from the room (by an amount equal to work done by the compressor). Therefore, temperature of room will increase and so it will be warmed gradually. As according to 2nd law of thermodynamics, heat cannot be transferred on its own, from a body at lower temperature to another at higher temperature.

Q.19. Assertion: The heat supplied to a system is always equal to the increase in its internal energy.
Reason: When a system changes from one thermal equilibrium to another, some heat is absorbed by it.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (d)
According to first law of thermodynamics, ΔQ = ΔU + ΔW = ΔU + PΔV. If heat is supplies in such a manner that volume does not change ΔV = 0 i.e., isochoric process, then whole of the heat energy supplied to the system will increase internal energy only. But, in any other process it is not possible. Also heat may absorbed or evolved when state of thermal equilibrium changes.

Q.20. Assertion: The entropy of the solids is the highest
Reason: Atoms of the solids are arranged in orderly manner.
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c) If assertion is true but reason is false.
(d) If the assertion and reason both are false.
(e) If assertion is false but reason is true.

Correct Answer is option (a)

Entropy is a measure of the disorder or randomness of the system. Greater the randomness, greater the entropy.