Based on the context, what is the best definition of the word illusion?

If an atom has no charge, what can we say about the subatomic particles in the atom? a) there will be the same number of protons and neutrons, but a different number of electrons. b) there will be the same number of electrons and neutrons, but a different number of protons. c) there will be the same number of protons and electrons.

So know lets geta real question what does this actually mean

What is the meaning of calculated as it is used in this sentence from "ups and downs"? he calculated that the ride would be over before she could finish the ice cream sundae he bought her. a estimated b solved c analyzed d clarified