The present book is an efforty to meet the requirement of the students of B.A/B,Sc.II Paper III Of K.U.Kurukshetra,M.D.U Rohtak and other Indian Universities which have accepted the new syllabus os UGC.The objective behind the book is to make the subject clear to the students,For this purpose a number of books have been consulted and the articles and examples have been solved in detail.