How many protons are in an atom?

Answer 1

It depends entirely on the identity of the atom. Each element has a unique number of protons. In fact, the number of protons in an atom is what tells you what element it is! For instance, hydrogen (H) has 1 proton, carbon (C) has 6 and copper (Cu) has 29.
If you look at the Periodic Table, than you'll see that each element in the table has a number. That number is called the atomic number, and that number is exactly equal to the number of protons in that particular element's nucleus.

See the Web Links to the left of this answer for a periodic table

Answer 2

The number of protons in an atom is equal to its atomic number, which is a unique identifier for each element. Each proton carries a positive charge and contributes to the overall positive charge of the nucleus of an atom.