2. Explain the rules for naming a binary compound from its formula.

The answer to this question is given below in this explanation section.

Explanation:

A binary ionic compound, a metal will always be the first element. in the formula,While a nonmetal will always be the second.The metal cation is named first,followed by the nonmetal anion.Subscript in the formula do not effects the name.

The overall charge of the compound is zero.Potassium ion is k+,While fluoride ion is F-,Since the magnitude of the charges is this would also be the case for a compound such as MgS,in which the ions are Mg2+ and S2-,For sodium nitride the sodium ion is Na=while the nitride ion is N3-.

none, its a machine

3. dark matter

empty space could also be a simple vacuum