10. Since iron is a transition metal with multiple oxidation numbers, which Fe is bonded in the formula iron oxide Fe2O3?

its first and third is your answer i did the qustion the fourth isnt right

there are two significant figures.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.