Question 4 (a) For the surface-catalysed gas-phase reaction A (9) +B (g) P(s). suppose the product, P can be adsorbed. Derive the form of the rate law according to the Langmuir-Hinshelwood model, if: (0) A, B and P are all moderately adsorbed. (i) A and B are weakly adsorbed and P is strongly adsorbed. [12 marks] (b) What is the value of effectiveness factor (n) for very large and very small values of Thiele modulus (6)? Discuss the physical meaning of these values with appropriate diagram [8 marks] (c) For a zero-order catalytic reaction, if the catalyst particle effectiveness factor is n. what is the overall effectiveness factor (n.) in terms of n? Justify your answer. [5 marks] [Total 25 marks]