Share on mother's property

it has become her self acquired property, so she has all the right to do what she wants. If she dies intestate the property will devolve upon you, if u r sole legal heir.

You have posted number of queries in one go, however, answer to the same are:

1.What are the chances of claiming the properties back? Remote

2. Can she sell them without my approval or transfer them to some one else?  Yes it is her self-acquired property despite the fact that she doesn't have any income and bought with your money.

3. Does she has the complete ownership on the properties? Yes.

 4. Whether my son has any right on the above said properties as per Joint Family rule? If your mother do not dispose it of to some other person your son may get it by will, gift or any other document in his name, otherwise no.

5. Can she sell the properties without my signature? Of course she can disopose of as she likes.

6. My son is a minor, so not sure whether she needs his signature or not during registration. It is a vague query.

Engage/Contact a local lawyer

Simple answers to your both the questions are:  1) Yes,  2) No