Free First Law of Thermodynamics MCQs with Answers

• A. -420 J
• B. 420 J
• C. 80 J
• D. -80 J

Explanation: According to the First Law of Thermodynamics:Q = ΔU + WAs in the question, the internal energy is decreased by 300J, so ΔU will be -300J.

• A. dQ
• B. dW
• C. dQ-dW
• D. dQ+dW

Explanation: The quantity that remains unchanged is known as a state function, which depends only on the initial and final states of the system and is…

• A. Independent
• B. Dependent
• C. Highly dependent
• D. Not enough information

Explanation: Option A: The internal energy of a system is independent of the path taken to reach a particular state.

• A. Yes. The temperature can rise if work is done by the gas.
• B. No. The only way that the temperature can rise is if heat is added to the gas.
• C. Yes. The temperature can rise if the work is done on the gas.
• D. No. The only way that the temperature can rise is by adding more molecules in container.

Explanation: In a thermally insulated system, where no heat can flow between the gas and its surroundings, the change in internal energy of the gas is…

• A. Difference between the heat given to the system and work done by the system appears as internal energy of the system
• B. Difference between work done and the change in internal energy is equal to the heat absorbed by the system
• C. Some of the heat absorbed and the increase in internal energy is equal to the work done by the system
• D. Some of the heat absorbed and the work done by the system is equal to the decrease in the internal energy of the system

Explanation: The First Law of Thermodynamics states that the internal energy of the system is equal to sum of heat given to the system and work done by…

• A. Internal energy = decrease direction of kinetic energy = heat released from the gas
• B. Internal energy = decrease direction of transfer of thermal energy = heat absorbed by the gas
• C. Internal energy = increase direction of transfer of thermal energy = heat released by the gas
• D. Internal energy = increase direction of transfer of thermal energy= heat absorbed by the gas

Explanation: In isovolumetric change, volume doesn't change so no work can be done so heat can only be transferred in the form of thermal energy and…

• A. Isothermal process
• B. lsochoric process
• C. Adiabatic process
• D. Isobaric process

Explanation: OPTION A: The thermodynamic process which is carried out in such a way that a system undergoes changes but its temperature remains…

• A. 8900J
• B. 8800J
• C. 7900J
• D. 7500J

Explanation: According to the equation of the First Law of Thermodynamics,U = Q - WU = change in internal energyQ = heat absorbedW = work doneAlso note…

• A. No heat is added to or taken out of a system
• B. No change of temperature takes place
• C. Boyle's law is applicable
• D. Pressure and volume remain constant

Explanation: An adiabatic process is defined as a process in which no heat transfer takes place.

• A. W=0
• B. Q=W=0
• C. E=0
• D. Q=0

Explanation: In a cyclic process, as initial and final states are the same, change in internal energy is zero (E = 0).

• A. Same
• B. Different
• C. May be same
• D. Not enough information

Explanation: The change in internal energy if a system depends only on initial and final states of the system and not on path followed .

• A. Transfer of heat by radiation
• B. Electrical heating by nichrome wire
• C. Transfer of heat by conduction
• D. Isothermal compression

Explanation: Option D is correct as "isothermal expansion or compression" is reversible so long as the piston motion is sufficiently slow such that at…

• A. 2J
• B. 1J
• C. -1J
• D. -2J

Explanation: The work done during adiabatic expansion can be calculated using the First Law of Thermodynamics, which states that the change in internal…

• A. dU = -dW in Adiabatic Process
• B. dU = dW in Isothermal Process
• C. dU = dW in Adiabatic Process
• D. dU = -dW in Isothermal Process

Explanation: In an Adiabatic process, the total heat is given by;Q = dU + dWWe also know that for an adiabatic process, Q = 0, therefore the equation…

• A. 1/2
• B. 1/4
• C. 3/4
• D. 1

Explanation: Option A is correct since the formula of efficiency for a heat engine is 1-(T2/T1).

• A. nR/(γ-1)(T1-T2)
• B. nR/(γ-1)(T2-T1)
• C. nR(T2-T1)
• D. R(T2-T1)

Explanation: Option A is correct since it gives the correct statement for the work done in an adiabatic process.

• A. 2*Initial
• B. Initial heat
• C. Initial internal energy
• D. Initial work

Explanation: According to the first law of thermodynamics, the internal energy of a system is conserved.

• A. Decreasing the temperature of high temperature reservoir
• B. Increasing the temperature of high temperature reservoir
• C. Increasing the temperature of low temperature reservoir
• D. Increasing the temperature of both high temperature reservoir and low temperature reservoir

Explanation: The efficiency of a Carnot engine depends on the temperature of hot and cold reservoirs.The larger the temperature difference between the…

• A. Q2 - 1/Q1
• B. Q2 + 1/Q1
• C. Q2 + Q1
• D. 1- Q2/Q1

Explanation: The efficiency of a heat engine is typically defined as the ratio of the useful work output to the heat input.

• A. Newton's law
• B. Charles' law
• C. Conservation of energy
• D. Conservation of entropy

Explanation: The first law of thermodynamics is essentially an expression of the law of conservation of energy applied to thermodynamic systems.