There are 2 parts to your question.
Firstly, the sale proceeds of the sites will be subject to capital gains. So depending on the price at which you bought the site, you will need to pay Capital gains on the difference. To be exempt from the capital gains tax, you will need to invest the sale proceeds in a residential apartment or in the bonds as specified under section 54EC.
Secondly, regarding investments in FD's, the interest will be taxable. However, if you do not have any other source of income, then the interest on Rs. 11 lakhs will be below the taxable threshold and there will be no taxes.
But if you invest in FD's you will have to pay Capital Gains tax.
Hope that clarifies.