If it has been held for more than 2 years it will be a long term capital gain so tax would be chargeable @20% and you can take benefit of various exemption section.
If you purchase another land you won't save any tax.
You can avoid by eitgei investing capital gain in bonds or sale proceeds in purchase or construction of flat.
If you are purchasing flat then you can save entire tax. No tax even if entire sale proceeds is transferred to the seller of flat. But you need to deduct his TDS if amount of flat is above 50 lakh.
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