Right to Property - Ancestral or Acquired

Sir/Madam, History in brief: 1. Father's mother bought land in 1950. 2. She passed away in 1970 and divided said land 50-50 between 2 sons (one of them being my father). 3. Father sold his share of land in 1980 and made 1 building. Then sold this building and made 2 apartments. 4. One apt he sold and funded purchase of another apt for my brother in 1986. The second apt he lived in and decide to hand over to me on his passing away. 5. He passed away without signing a will. He is survived by his wife (my mother) and 2 sons (self being one of them). Current Status: 6. My mother claims the house is hers and may leave it to me in her will. 7. My brother claims a share in this second apt as well in the absence of a signed will by my father, even though he has already been given an apt in 1986 by my father. Questions: a] Status of second apt: Is this second apt in which my father lived with his wife ancestral or acquired property? b] In absence of will how is this property to be divided? c] The house in which my brother lives (funded by my father as explained above) is in my brother's name. Can I lay counter claim to my brother's house as he does this one on basis it was also financed by my father? d] Is there any regulation under which I can force him to accept fair compensation (market value of his fair share in property) and surrender his interest in the apt in exchange? Thank you for your advice, please. Sincerely, Bharat Shahane