(a) The following sets of N2 adsorption data were obtained at 77 K using a commercial rapid-adsorption analyzer for three samples (each about 0.25 g) of H-ZSM-5 with Si:AI ratios of 12 to 70. From these data calculate the monolayer volume Vm and BET surface area for each sample. Compare the surface areas for the three different samples. Explain how it is possible to have significant variations in surface area for the same zeolite structure. Volume N; Adsorbed (cm' STP/g) ZSM 5 (Si/AI-12) ZSM-5 (Si/AI -30) ZSM 5 (Si AI-70) 104.941 110.752 113.994 116.206 118.345 Relative Pressure (P/P.) 0.05 0.1125 88.953 92.21 94.765 96.124 107.236 113.518 117.974 121.181 123.309 0.175 0.2375 0.3001 97.27 (b) Why is measurement of metal surface area important? List at least twvo reasons.