Tax implications of Advance receipt for Property sale ale

Sir iam planning sell a residential property, due to present government rules property can not be registered at present, buyer is ready to pay 75% of total value and take possession of property based on the agreement, balance 25% will be paid at the time of registration which may take 1 to 2 years.. Sir my query is how to show advance income in ITR, whether any capital gain tax needs to be paid, whether I get exempt if invested in another residential property prior to the registration of original property