Registered socity under societies act

If the General Body with 2/3rds or 3/5th majority approve the proposal to sell the property and shall deposit in the society account. In the approval, the GB shall approve with a condition that either the President/Secretary/Treasurer any of two executive members shall sign in the document.

Thank you. If they sell less than market value and more than guideline value. Whether any other person can file a case saying that the property sold less than market value and challenge. 

As per Tamilnadu societies registration act there is no bar for a society to transfer the immovable property for the benefit of the society and not for the benefits of its members. Approval of the Registrar of Societies is required for mortgaging it's immovable property. Within the ambit of the byelaws the society can sell its property unless it is barred by law. 

The society can sell the property above the guidelines value 

What will happen if the socity sold the land without approval of registrar of socity

They can approach civil court with valid grounds.

It all depends on the history of formation of the society. Your question is about selling a  land. I presume that it is a vacant land with no building on it. All members of the society (to be formed) can jointly purchase the land and no building has yet been constructed. If so each member has an undivided share and all of them together only can sell the land. If a society is formed after the purchase, the article of association signed by all the owners should state that the title for the land is vested in the association. The article should also state the manner in which the land can be disposed of. If a building is constructed on the land the picture will completely change. In my opinion the Societies Registration Act is not suitable for this purpose. The Registrar or Charity Commissioner has nothing to do with the matter of selling the land and to adjudicate on it.

Land purchased from socity with out registrar approval. Is there any possibility that any other people can oppose this sale legally? In near future for reason like land sold less than market value some this like that?

It has been advised many times that the buyer should seek legal opinion from an experienced lawyer before purchasing an immovable asset, if not such issues will be a long stretched head ache