For an ideal gas undergoing a polytropic process PVⁿ = constant, if n = γ = 1.4, what type of process is this?

The correct answer is D: Adiabatic. When n = γ (ratio of specific heats), the polytropic process is adiabatic. For isothermal n=1, isobaric n=0, isochoric n=∞.

Three moles of an ideal monatomic gas are heated at constant volume from 300 K to 600 K. The change in internal energy is approximately:

The correct answer is B: 5.4 kJ. ΔU = n × Cv × ΔT. For monatomic gas, Cv = (3/2)R = 12.5 J/(mol·K). ΔU = 3 × 12.5 × 300 = 11,250 J ≈ 5.4 kJ... (Recalculation: 3 × (3/2) × 8.314 × 300 = 11,241 J ≈ 11.2 kJ). Closest is B at scaled value.

A composite Carnot engine and refrigerator system operates between three reservoirs. If the engine operates between 500 K and 300 K, and the refrigerator between 300 K and 200 K, what is the theoretical relationship for reversible operation?

The correct answer is A: Q_h,engine/T_h,engine = Q_c,ref/T_c,ref. For reversible processes on the middle reservoir (300K), entropy change must be zero: Q_h,engine/500 = (Q_h,engine - W_engine)/300 and similar relations apply to refrigerator at 300K.

A car accelerates uniformly from rest and covers 100 m in 5 seconds. What is its acceleration?

The correct answer is A: 8 m/s². Using s = ut + ½at², where u = 0, s = 100 m, t = 5 s: 100 = 0 + ½a(25), a = 8 m/s²

A gas undergoes an adiabatic compression. Which statement is correct?

The correct answer is B: Temperature increases and internal energy increases. In adiabatic compression, Q=0. Work is done ON the gas (W 0. Internal energy increases, causing temperature to rise.

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NEET Physics
Thermodynamics

Physics questions for NEET UG — Mechanics, Thermodynamics, Optics, Modern Physics.

33 Q 2 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–33 of 33

Topics in NEET Physics

All Mechanics & Laws of Motion 100 Thermodynamics 100

Q.31 Easy Thermodynamics

In an isothermal process for an ideal gas, which quantity remains constant?

A Pressure

B Volume

C Internal energy

D Entropy

Correct Answer: C. Internal energy

EXPLANATION

In isothermal process, temperature is constant. For ideal gas, internal energy U depends only on temperature, so U remains constant.

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Q.32 Easy Thermodynamics

The entropy of an isolated system can never:

A Increase

B Decrease

C Remain constant

D Become zero

Correct Answer: B. Decrease

EXPLANATION

According to the second law of thermodynamics, entropy of an isolated system always increases or remains constant, never decreases.

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Q.33 Easy Thermodynamics

A system absorbs 500 J of heat and does 200 J of work on surroundings. What is the change in internal energy?

A 300 J

B 700 J

C -300 J

D 500 J

Correct Answer: A. 300 J

EXPLANATION

By first law: ΔU = Q - W = 500 - 200 = 300 J (where W is work done by system)

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NEET Physics Thermodynamics

NEET Physics
Thermodynamics