Chemical Engineering questions for GATE and PSU exams are built on a handful of core subjects applied in many ways. Practice spans fluid mechanics, heat transfer, mass transfer, chemical reaction engineering, thermodynamics, process control and instrumentation, and plant design economics. Numerical solutions carry the assumptions written out, because the assumption is usually what separates a correct answer from a plausible one.
Which of the following is NOT an extensive property?
Answer: B
Temperature is an intensive property as it does not depend on the quantity of substance. Volume, mass, and internal energy are extensive properties that depend on the amount of material.
Q.2Easy
According to the first law of thermodynamics, ΔU = Q - W. In this equation, W represents:
Answer: B
In the convention ΔU = Q - W, W is work done by the system. This is the IUPAC recommended convention used in most thermodynamics calculations.
Q.3Easy
A system absorbs 500 J of heat and does 200 J of work. The change in internal energy is:
Answer: A
Using ΔU = Q - W, where Q = +500 J (absorbed) and W = +200 J (work done by system). Therefore, ΔU = 500 - 200 = 300 J.
Q.4Easy
The compressibility factor Z for an ideal gas is:
Answer: B
For ideal gas, Z = PV/nRT = 1 always. For real gases, Z ≠ 1 due to intermolecular forces and molecular volume.
Q.5Easy
In a constant pressure calorimeter, 1 kg of water is heated from 25°C to 75°C. Heat absorbed is approximately (Cₚ of water = 4.18 kJ/kg·K):
Which process is represented by a horizontal line on a T-S (Temperature-Entropy) diagram?
Answer: C
On a T-S diagram, horizontal line means constant temperature (T = const), which is an isothermal process. A vertical line would represent isentropic process (S = const).
Q.7Easy
A gas mixture contains N₂ (40% mole) and O₂ (60% mole) at 1 atm and 298 K. Calculate the partial pressure of O₂ in the mixture.
The equation of state for a real gas that considers molecular volume and intermolecular forces is:
Answer: B
This is the van der Waals equation where 'a' accounts for intermolecular forces and 'b' for molecular volume
Q.14Easy
A system undergoes a process where Q = 100 J and W = 60 J. The change in internal energy is:
Answer: B
ΔU = Q - W = 100 - 60 = 40 J (First Law of Thermodynamics)
Q.15Easy
A reversible adiabatic process is also known as:
Answer: A
A reversible adiabatic process has constant entropy (dS = 0), which defines an isentropic process. This is a fundamental concept in thermodynamics.
Q.16Easy
The enthalpy change for a constant pressure process equals:
Answer: A
At constant pressure, ΔH = qₚ (heat at constant pressure). This is the definition of enthalpy and its primary application.
Q.17Easy
In a constant volume process, the heat added to the system equals:
Answer: A
For constant volume: W = 0, so Q = ΔU from first law (ΔU = Q - W). This is isochoric process where all heat goes to internal energy change.
Q.18Easy
A system absorbs 500 J of heat and does 200 J of work on surroundings. The change in internal energy is:
Answer: A
First Law: ΔU = Q - W. Q = +500 J (absorbed), W = +200 J (work by system). ΔU = 500 - 200 = 300 J. Positive indicates internal energy increases.
Q.19Easy
At constant temperature and pressure, which of the following represents the Gibbs free energy change for a spontaneous process?
Answer: B
For a spontaneous process at constant T and P, ΔG must be negative. ΔG = 0 indicates equilibrium, and ΔG > 0 indicates non-spontaneous process.
Q.20Easy
The Clausius-Clapeyron equation relates vapor pressure to temperature. Which statement is correct?
Answer: A
Clausius-Clapeyron equation (d ln P/dT = ΔH_vap/RT²) applies specifically to phase equilibria and shows direct relationship between vapor pressure and temperature.
