Chemical Engineering GATE 2025 Questions with Answer

Ques 53 Mass Transfer

A binary AB liquid mixture containing 30 mol% A is subjected to differential (Rayleigh) distillation at atmospheric pressure in order to recover 60 mol% A in the distillate. Assuming a constant relative volatility α_AB=2.2. the average composition of the collected distillate is ______ mol% A (rounded off to nearest integer).

Ques 54 Mass Transfer

Gas containing 0.8 mol% component A is to be scrubbed with pure water in a packed bed column to reduce the concentration of A to 0.1 mol% in the exit gas. The inlet gas and water flow rates are 0.1 kmol/s and 3.0 kmol/s, respectively.
For the dilute system, both the operating and equilibrium curves are considered linear. If the slope of the equilibrium line is 24, the number of transfer units, based on the gas side, N_OG is ______ (rounded off to 1 decimal place).

Ques 55 Mass Transfer

Solute A is absorbed from a gas into water in a packed bed operating at steady state. The absorber operating pressure and temperature are 1 atm and 300 K, respectively. At the gas-liquid interface y_i=1.5 x_i where y_i and x_i are the interfacial gas and liquid mole fractions of A, respectively. At a particular location in the absorber, the mole fractions of A in the bulk gas and in the bulk water are 0.02 and 0.002, respectively. If the ratio of the local individual mass transfer coefficients k_y/k_x=2 for the transport of A on the gas-side (k_y) to that on the water-side (k_x), then y_i equals ______ (rounded off to 3 decimal places).

Ques 56 Mass Transfer

A wet solid of 100 kg containing 30 wt% moisture is to be dried to 2 wt% moisture in a tray dryer. The critical moisture content is 10 wt% and the equilibrium moisture content is 1 wt%. The drying rate during the constant rate period is 10 kg/(h m²). The drying curve in the falling rate period is linear.
If the drying area is 5 m², the time required for drying is ______ h (rounded off to 1 decimal place).
Note: All the moisture values given are on dry-solid basis.

Ques 57 Mechanical Operations

A leaf filter is operated at 1 atm (gauge). The volume of filtrate collected (V in m³) is related with the volumetric flow rate of the filtrate (q in m³/s) as: 1/q = 1/(dV/dt) = 50V+100.
The volumetric flow rate of the filtrate at 1 hour is ______ × 10^-3 m³/s (rounded off to 2 decimal places).

Ques 58 Plant Design and Economics

The capital cost (CC) of an industrial equipment varies with its capacity (S) as CC ∝ S^β. The rule-of-thumb value of the exponent β is

Ques 59 Plant Design and Economics

It is proposed to install thermal insulation in a residence to save on the summer-monsoon season air-conditioning costs. The estimated yearly saving is 20 thousand rupees. The cost of installation of the insulation is 150 thousand rupees. The life of the insulation is 12 years. For a compound interest rate of 9% per annum, the minimum salvage value of the insulation for which the proposal is competitive, is ______ thousand rupees (rounded off to nearest integer).

Ques 60 Thermodynamics

The number of independent intensive variables that need to be specified to determine the thermodynamic state of a ternary mixture at vapor-liquid-liquid equilibrium is

Ques 61 Thermodynamics

The boundary of a system does not allow exchange of either mass or energy (in the form of heat and/or work) with the surroundings. The system is termed

Ques 62 Thermodynamics

The following data is given for a ternary ABC gas mixture at 12 MPa and 308 K:

Ques 63 Thermodynamics

Ideal nonreacting gases A and B are contained inside a perfectly insulated chamber, separated by a thin partition, as shown in the figure. The partition is removed, and the two gases mix till final equilibrium is reached. The change in total entropy for the process is ______ J/K (rounded off to 1 decimal place).GIVEN: Universal gas constant R=8.314 J/(mol K)

Ques 64 Thermodynamics

An ideal monoatomic gas is contained inside a cylinder-piston assembly connected to a Hookean spring as shown in the figure. The piston is frictionless and massless. The spring constant is 10 kN/m. At the initial equilibrium state (shown in the figure), the spring is unstretched. The gas is expanded reversibly by adding 362.5 J of heat. At the final equilibrium state, the piston presses against the stoppers. Neglecting the heat loss to the surroundings, the final equilibrium temperature of the gas is ______ K (rounded off to the nearest integer).

Ques 65 Thermodynamics

Components A and B form an azeotrope. The saturation vapour pressures of A and B at the boiling temperature of the azeotrope are 87 kPa and 72.7 kPa, respectively. The azeotrope composition is ______ mol% A (rounded off to the nearest integer).
GIVEN: ln(γ_A/γ_B)=0.9(x_B²-x_A²)