Tax liability on returning nri

I am Indian Citizen ,I was in Hongkong for 8 years from June 2008 to June 2016 & have returned back to India in June 2016 . I have following queries with regard to taxation in India for the house ( flat )bought in Hongkong in June 2011 (which is still under mortgage). Let me know the following : 1. What is the tax liability in India if flat is sold within 2 years of returning back to India( while I am resident but not ordinary resident ) and if flat is sold after 2 years . Understand that global income is taxable in India ,however first two years global income will not attract income tax in India . 2. Can the benefit of indexation be taken for overseas property ?If yes , how will it be calculated ? 3. Since property was bought in Hongkong (from income earned in HK) , it was bought in HK dollars and will be sold in Hongkong dollars . There are two ways to calculate capital gain . a)Capital Gain = (Selling price in HK dollar - Purchase Price in HKD ) X present rate of HKD in rupees b)Capital Gain = (Selling price in HK dollar X Present rate of HKD in rupees ) -( Purchase price in HK dollar X HK dollar rate in INR at the time of purchase ). Please advise which way capital gain be calculated 4) Is there any way to save on tax if nationality is changed in Hongkong . It is to inform you that there is no DTAA between Indian and Hongkong .