Which of the following is an intensive property in thermodynamics?
Answer: A
Temperature is an intensive property as it does not depend on the quantity of matter. Mass, volume, and weight are extensive properties.
Q.2Easy
The First Law of Thermodynamics is a statement of conservation of:
Answer: B
The First Law of Thermodynamics states that energy cannot be created or destroyed, only converted from one form to another.
Q.3Easy
For an ideal gas undergoing an isothermal process, the change in internal energy is:
Answer: B
In an isothermal process, temperature is constant. For an ideal gas, internal energy depends only on temperature, so ΔU = 0.
Q.4Easy
The entropy of a reversible adiabatic process is:
Answer: C
A reversible adiabatic process is also called isentropic, meaning entropy remains constant (ΔS = 0).
Q.5Easy
Which process requires zero work to be done by the system?
Answer: B
In an isochoric (constant volume) process, W = ∫PdV = 0 because volume does not change.
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Q.6Easy
A heat engine operates between temperature reservoirs of 500 K and 300 K. What is the maximum possible efficiency of this engine?
Answer: A
Maximum efficiency is Carnot efficiency = 1 - (T_cold/T_hot) = 1 - (500300) = 0.4 = 40%
Q.7Easy
What is the first law of thermodynamics in differential form?
Answer: A
The correct form is dU = δQ - δW, where δW = PdV for expansion work. This represents energy conservation in thermodynamic systems.
Q.8Easy
What is the relationship between specific heats C_p and C_v for an ideal gas?
Answer: B
The Mayer relation: C_p - C_v = R, where R is the specific gas constant. This relation holds for all ideal gases.
Q.9Easy
A reversible adiabatic process for an ideal gas is also known as:
Answer: C
A reversible adiabatic process has constant entropy (dS = 0), making it isentropic. This is a key assumption in many thermodynamic analysis for ideal processes.
Q.10Easy
Which thermodynamic property is NOT a state function?
Answer: C
Heat (Q) and work (W) are path-dependent quantities, not state functions. Internal energy, enthalpy, and entropy are state functions depending only on initial and final states.
Q.11Easy
A gas undergoes an isobaric process. If 500 J of heat is added and the gas expands such that work done by the gas is 200 J, what is the change in internal energy?
Answer: A
From first law: ΔU = Q - W = 500 - 200 = 300 J. Internal energy increases by 300 J.
Q.12Easy
Which of the following has the highest specific heat capacity among common substances at room temperature?
Answer: A
Water has exceptionally high specific heat (~4.18 kJ/kg·K), much higher than metals (iron ~0.46) and air (~1.01). This is due to hydrogen bonding in water.
Q.13Easy
In a constant volume process, 300 J of heat is removed from a gas. Calculate the work done and change in internal energy.
Answer: A
In constant volume process: W = ∫PdV = 0. From first law: ΔU = Q - W = -300 - 0 = -300 J
Q.14Easy
What is the SI unit of entropy?
Answer: A
Entropy is defined as dS = dQ_rev/T. Units: Joules/Kelvin = J/K. This is the fundamental SI unit for entropy.
Q.15Easy
If the specific heat at constant volume (Cv) for a diatomic ideal gas is 5R/2, what is its specific heat at constant pressure (Cp)?
Answer: A
Using Mayer's relation: Cp - Cv = R. Therefore, Cp = 5R/2 + R = 7R/2
Q.16Easy
A system undergoes a cyclic process. The net work done by the system is 150 kJ and the net heat absorbed is 150 kJ. Which statement is correct?
Answer: B
For any cycle: ΔU_cycle = 0. First law: Q_net = W_net confirms energy conservation. 150 = 150 ✓
Q.17Easy
Which of the following processes has zero work done by/on the gas?
Answer: B
Work W = ∫P dV. In isochoric process, dV = 0, therefore W = 0 regardless of pressure or temperature changes.
Q.18Easy
Which statement correctly describes the second law of thermodynamics?
Answer: B
The Clausius statement of second law: For isolated systems, dS_universe ≥ 0. dS = 0 for reversible, dS > 0 for irreversible processes.
Q.19Easy
For a substance, the triple point and critical point data are important in phase diagrams. At the triple point, how many phases can coexist?
Answer: C
At the triple point, solid, liquid, and vapor phases are in thermodynamic equilibrium. For water, this occurs at 273.16 K and 611.657 Pa.
Q.20Easy
A gas mixture contains N2 (40%) and O2 (60%) by mole fraction. What is the partial pressure of N2 if total pressure is 5 bar?
Answer: A
By Dalton's law: P_N2 = x_N2 × P_total = 0.40 × 5 = 2 bar
