Tax??

Whatever amount you are getting or got from selling the land is taxable under the capital gain.  If you don't want to pay the tax then invest it in the capital gain expempt schemes.  

If you kept the money and CBI raids and seized the amount then to get it release the amount you will have to show the documents to show that how you got that money>

white money dont mean that you would not be liable to pay taxes. If the property was purchased for 5 lakhs in a year than the indexed cost of purchase would need to be calculated and the difference between Rs 70 lakhs and the indexed cost of purchase would be taxable as long term capital gain. There are some prescribed investment options if the capital gain is invested there no tax will be chargeable on this money.

Normally CBI dont raid and that too for just property sale transactions.

If you sold the property after 3 years' from the date of its purchase by you, then you are liable for payment of long term capital gains tax.  However, if your invest the said amount for purhcase of another dwelling house for you within precribed time frame or if you invest the same in notified  investment scheme like infrastructure Bonds, you will be exempted from the liability of payment of tax.