Atomic mass deals with the number of protons and neutrons added together, atomic number deals with protons only, though isotopes can be explained like this, say you had a hydrogen atom it's one proton and one electron if you add a neutron to it, the hydrogen becomes Deuterium which is a isotope of hydrogen it's the same atom just a neutron added to it for a different atomic mass if only slightly changed
Electrons are negatively charged. If you remove negative particles, the leftover atom is positive and positive is really just another word for "less negative".
The factors responsible for causing a reaction to go to completion.
The correct answer is C. The weight downward and the friction moving forward creates thermal energy through kinetics and melts a tiny bit of the ice making it slick enough for the skate to slide.
