Which of the following is true about a theory

In science, a theory is not merely a guess. a theory is a fact-based framework for describing a phenomenon. A theory presents a concept or idea that is testable. While a hypothesis is a proposed explanation for a phenomenon.

So the correct option is ' Theory is based on experiment while a hypothesis is related to observation'.

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.