Using basically the impulsive approximation and a modification of the method used by Alladin S.M., (1965, Ap.J.,141, 768), and described in detail in Chatterjee T.K., (1990, IAU Col.,124, 519, 569) we study the evolution of binary interacting galaxies, leading ultimately to mergers. Each collision is characterised by the initial separation between the galaxies and the relative velocity therein. In each case the orbital evolution and largescale structural changes in the galaxies are studied by taking into account the change in relative velocity due to dynamical friction, leading ultimately to mergers. The evolution is considered from a time when the gravitational interaction between the progenitor pairs is physically significant (Chatterjee, 1992, Astroph. Sp.Sc., in press).