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Part-IResults and DiscussionThe MDS generates different descriptors belonging to different categories likeconformational, electronic, shape, spatial, thermodynamic, etc. Interpretation of QSARmodels with more terms becomes difficult for QSAR. Moreover all the terms may not berelevant. Multiple regression was run several time taking different calculated descriptorsto obtain the equation with high coefficient of determination (r 2 ).Further, the biological activity has been expressed in by different expressions viz. pH ofGastric Secretion, Total Acidity, Volume of Gastric Secretion and Ulcer Score of whichpH of Gastric Secretion and Total Acidity are inter correlated therefore, only total aciditywas selected for the present study. Thus, we had three different expressions of thebiological activity. The biological activity for all the three expressions was taken as thelog values of its inverted figures.Thus, to summarize, the QSAR study was performed for two series of compounds, inwhich three main sets of biological activities per series was used.A. 5-H benzimidazole Series:1. Total Acidity:Description of the descriptors used in the final equation:1. Quadrupole2This descriptor signifies magnitude of second tensor of quadrupole moments and isdirectly proportional to the activity.2. T_C_O_2This is the count of number of carbon atoms (single, double or triple bonded)separated from any oxygen atom (single or double bonded) by 2 bond distance in amolecule and is inversely proportion to the activity.3. chi4pathClusterThis descriptor signifies molecular connectivity index of 4 th order pathcluster and isdirectly proportional to activity.Of these the best equation was given as under:Acidity log(1/C) = + 0.0044(± 0.0000) Quadrupole2 - 0.0792(± 0.0121) T_C_O_2+ 0.1386(± 0.0547) chi4pathCluster -1.9411…………..(Equation-1)149