ENQUIRY ABOUT TAX LIABILITY

There would be long term capital gain over sell of your ancestral property share, but it would be exempted under sec. 54 of IT act, as investment in new HP.

In short, there would not be any long-term capital gains TAX liability.

What's the capital gain on selling ancestral property. Cost of accquisition and capital gain.

You need to take indexation cost of aquisition. as the ancestral property is purchased before 2001 you need to take FMV as on 01/04/2001 to calculate indexation cost of aquisition.(ICOA)
deduct this ICOA and cost of improvements /indexation cost of improvements, if any from the fair value of consideration you received to get long term capital gain.

as another housing property was purchase d in same financial year.first purchased there after  ancestral property sold.then what is tax implications.

i wish to know whether section 54 of IT act will apply or not

If it is purchased before 2001 then are some seperate provisions as such. You need to take some provisions.

Why you attempt to confuse more?  

Question is for Sec. 54 applicability, while answer is all together...