Conversion of agriculturala land into site

MY FATHER CONVERETED LAND  AGRICULTURLA LAND INTO SITE. WHILE REGD DOUCMENT  HE MADE ME AS PARTY AND ALLOAATED 12 SITES . I HAVE NOT SOLD ANY SITE NO. THE ITO PROPOSING TO LEVY INCOME TAX.  IAM NOT A REAL ESTASTE BUSINESS PERSON.  THE ITO IS LEVYING  CAPITAL GAIN TAX ON CONVERSION  PLEASE GUIDE ME WHETHRE  I AM LIABLE FOR TAX  IF SO WHAT IS TAX RATE. WHAT IS COST OF PURCHASE IN MY CASE