Subtopic: BET classification of sorption isotherms
Question Statement:
Most agricultural food grains and biological seed materials exhibit which Brunauer-Emmett-Teller (BET) classification of sorption isotherm?
Options:
(A) Type II (sigmoidal S-shaped curve)
(B) Type I (Langmuir monolayer plateau)
(C) Type III (purely convex Flory-Huggins)
(D) Type IV (flat stepwise capillary)
Answer Key:
A
Step-by-Step Solution & Explanation
Food grains and biological materials exhibit Type II sigmoidal isotherms: a concave monolayer sorption region at low $a_w$, an approximately linear multilayer region at intermediate $a_w$, and a steep convex capillary condensation region at high $a_w$ ($a_w > 0.7$).