Neutrons are neutral, which means they don't exactly have an electrical charge. It's because of this neutral charge that it is represented with a '0'.
On the other hand, protons and electrons <em>do </em>have electrical charges. Electrons flow around the outside of the nucleus, with a negative charge.
Protons are stored in the nucleus with the neutrons, holding a positive charge.
Here are some tips to help you remember the difference between protons, neutrons, and electrons.
Protons-- Think pro. Pro means positive (as in pros and cons) and the proton is often represented with the + sign. +, positive, pro, proton.
Neutrons-- Neutron sounds like neutral. Neutrally charged particles are often represented with an O. I personally think of Jimmy Neutron here. Every time his inventions went bad, his friends would say things like "Oh boy." O, Jimmy Neutron, neutron.
Electrons-- Think about how negative the United States are about the current president and how he was ELECTED. The - sign represents electrons. -, negative, presidential election, electron.
So the answer to your problems would be: 1. B-- electrons are negative 2. A-- protons are positive 3. C-- neutrons are neutral