S. 54F : Capital gains-Investment in a residential house–Purchase of flat from builder-Date of allotment to be taken as date of acquisition of property-House consisted of several independent units–Exemption cannot be denied–New house need not be purchased exclusively in the name of the assesee-Invested prior to date of filing of return u/s. 139(4)–Eligible for exemption. [S. 45, 139(1), 139(4)]