S. 54 : Capital gains-Investment in a residential house-Assessee constructing nursing home and residential house on land purchased from sale proceeds-Exemption not available in respect of entire land but only on portion of land on which residential house constructed and appurtenant thereto-Authorities failing to compute vacant land appurtenant to residential house-Assessing officer to consider all these aspects for purpose of computing exemption-Assessee entitled to benefit of indexation.[S. 45]