1. What determines the ampacity of a wire?
2. what is the maximum spacing between supports for rigid nonmetallic conduit trade size of a. 1 inch b. 2 inch ?
3.what is the difference between type AC and type ACT atmored cables?

These questions sound suspisiously like homework. Please explain why you need to know. Neither question is related to another.

All of these questions could be answered in the NEC 2011.

All of these questions could be answered in the NEC 2011.
That's nice, considering these questions were asked in 2006.