Adding or removing protons from an atom does what to the atom

Changes the element of the atom.

Explanation:

The elements are classified by the number of protons they have in their nucleus, so if the number of protons is changed (added or removed), that atom will become one of a different element.

For example, hydrogen has only 1 proton in its nucleus, and helium has 2. So if a proton is added to a hydrogen atom, it becomes a helium atom, and consequently its atomic number, wich is determided by the protons in an element, will also change.

if you already have the answer to (a), then just work out how many periods there are in 1 minute, and that's the answer to (c).

increase masses, decrease separation