Yes, it may attract capital gain tax depending on your sale value.
You have to get your property valued from registered valuer as on 01.04.1981 and then multiply it with 11.25 in case you are selling it before march 2017. This value will be your indexed cost of acquisition. Now deduct indexed cost of acquisition from sale value of the property and resultant value will be your capital gain amount.
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Thanks and Regards
Abhishek Dugar
CA CS B.Com