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GATE Mass Transfer: Leaching, liquid-liquid extraction, drying, humidification and adsorption – Previous Year Questions

11 GATE previous year questions on Leaching, liquid-liquid extraction, drying, humidification and adsorption (Mass Transfer, Chemical Engineering) with answers and explanations, from every paper.

  1. GATE 2022 CH Q33 (1 mark, Numerical answer) – A wet solid containing 20% (w/w) moisture (based on mass of bone-dry solid) is dried in a tray-dryer. The critical moisture content of the solid is…
  2. GATE 2022 CH Q57 (2 marks, Numerical answer) – The dry-bulb temperature of air in a room is 30 °C. The Antoine equation for water is given as Psat = 12.00 - 4000T - 40 where T is the temperature in…
  3. GATE 2023 CH Q23 (1 mark, Multiple choice) – Spray dryers have many advantages. Which one of the following is NOT an advantage of a typical spray dryer?
  4. GATE 2023 CH Q56 (2 marks, Numerical answer) – Partially saturated air at 1 bar and 50 °C is contacted with water in an adiabatic saturator. The air is cooled and humidified to saturation, and…
  5. GATE 2024 CH Q43 (2 marks, Multiple choice) – Alumina particles with an initial moisture content of 5 kg per kg dry solid are dried in a batch dryer. For the first two hours, the measured drying…
  6. GATE 2025 CH Q34 (1 mark, Numerical answer) – Oil is extracted from mustard seeds having 20 wt% oil and 80 wt% solids, using hexane as a solvent. After extraction, the hexane-free residual cake…
  7. GATE 2025 CH Q40 (2 marks, Multiple choice) – 500 mg of a dry adsorbent is added to a beaker containing 100 mL solution of concentration 100 mg phenol/(L solution). The adsorbent is separated out…
  8. GATE 2025 CH Q47 (2 marks, Numerical answer) – Consider moist air with absolute humidity of 0.02 (kg moisture)/(kg dry air) at 1 bar pressure. The vapour pressure of water is given by the equation…
  9. GATE 2025 CH Q65 (2 marks, Numerical answer) – 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…
  10. GATE 2026 CH Q38 (2 marks, Multiple choice) – Vapor pressure of water at various temperature is given in the table. Temperature (K) 284 289 294 299 310 --- --- --- --- --- --- Vapor pressure (kPa)…
  11. GATE 2026 CH Q39 (2 marks, Multiple choice) – A volatile organic compound (VOC) is to be adsorbed from air onto a bed of activated carbon. The equilibrium capacity of activated carbon at the feed…