Dr. Ali started negotiations in January, 2016 for the sale of his practice clinic. He stated that his average practice was worth Rs 2,000,000 per annum. The contract for the sale of practice with Dr. Usman was signed on May 1, 2016; between February 2016 to April 2016 the position of his practice had changed as his practice had fallen considerably owing to his illness and consequent absence from practice. Dr. Usman when took charge found that the practice was non-existent. Required:

In the context of Law of Contract, under what appropriate circumstance(s), Dr. Usman is entitled to rescind the contract and can recover the purchase amount of the clinic?