Cuantos electrones hay en los orbitales de azufre

The answer for #3 is c but i don't know why

The diagrams show objects’ gravitational pull toward each other. which statement describes the relationship between diagram x and y? gravity attracts only larger objects toward one another. gravity attracts larger objects only if they are close to one another. if the masses of the objects increase, then the force between them also increases. if distance between the objects increases, then the amount of force also increases.

What happens to isotopes that are unstable?