Income tax on purchse of house

My uncle wants to purchase a house for Rs 22 lacs. He has Rs 12 lakhs in a bank and want to paid remaining Rs 10 lakh in cash which is unaccounted. Can he do so?

His wife has a jewellery which can be sold for Rs 10 lakhs. Can he paid the said money for purchase of the house. Is there any cap gain tax liablility on it?

Or can he borrow Rs 10 lakhs as unsecured loan from his relatives?

Or is there any othe way?

Pls advise.