Subtopic: Controlled and modified atmosphere storage
Question Statement:
Apple is to be stored at 30 °C in modified atmosphere package of laminated films made of 150 μm thick polyethylene and 100 μm thick nylon. The partial pressures of oxygen outside and inside of the package are 0.21 atm and 0.01 atm respectively. The permeability values of polyethylene and nylon in m³ solute (STP) m⁻² s⁻¹ atm⁻¹ per m thickness are 4.17 × 10⁻¹² and 1.52 × 10⁻¹⁴ respectively.
Options:
(A) 138
(B) 183
(C) 381
(D) 813
Official Answer Key:
B
Step-by-Step Solution & Explanation
Resistance to permeation of each layer: R = L/P (thickness/permeability). R_polyethylene = 150×10⁻⁶/4.17×10⁻¹² = 3.597×10⁷; R_nylon = 100×10⁻⁶/1.52×10⁻¹⁴ = 6.579×10⁹. Ratio R_nylon/R_polyethylene = 6.579×10⁹/3.597×10⁷ = 182.9 ≈ 183, matching option (B).
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