GATE 2026 Chemical Engineering, Q20 · Mass Transfer
The correct answer is A, P-1, Q-2, R-3.
Question
A binary mixture of butane and butadiene is to be separated in an extractive distillation using furfural. Furfural lowers the activity of butadiene more than it does for butane. Match the component labels (X, Y, Z) in the distillation sequence shown with the chemical species (Butane, Butadiene, Furfural).
- A. P-1, Q-2, R-3
- B. P-1, Q-3, R-2
- C. P-2, Q-1, R-3
- D. P-2, Q-3, R-1
Official answer: P-1, Q-2, R-3
Why
GATE 2026 official key: (A). Furfural (Z) suppresses butadiene's volatility more than butane's, so butane leaves overhead as X and butadiene as Y: P-1, Q-2, R-3.
Explanation cross-checked for consistency. Final answer matches the official IIT answer key.