Capital gain under compulsory aquisition

Mr.X was a owner of a plot of urban land situated with in Municipal Limits purchased in 1972. On his demise in the year 1980 the said land was inherited by his wife Mrs. Y. During the year FY2006-07 the said land was compulsory acquired by the government. No valuation was done during the year 2006 and no value has been mentioned by the government in the documents of compulsory acquisition.During the FY 2015-16 a compensation has been granted in kind by providing a urban land within municipal limits. Further value of the same is not mentioned. However it is mentioned that the compensation is 15 of the value of the land compulsory acquired in FY2006-07.During the year FY2016 -17 Mrs. Y sold the land.1. What will be implication of capital gain on receipt of compensation in nature of land and how will it be taxable and on what amount.2. On sale of land in FY 2016 -17 what will be the nature of capital gain tax and what will be the cost of acquisition.