I don't believe the code has a set number, really just depends on what will be plugged into them. You wouldn't want ten microwaves on your circuit but for bedrooms, ten outlets will be fine. Outlet spacing is any wall bigger then 2 feet and no more then 12 feet in between them. Actually says something about that a lamp with a six foot cord placed anywhere along the wall shall be able to be plugged in to an outlet. A lot of the code book is about how we interpret it and then how an inspector does. Often time these interpretation are different.