Based on what you saw in the video, how do you think Earth's atmosphere has changed through Earth's history and how it continues to change.

i believe it is 40–40–20%

explanation:

i just learnt this recently but i need to look through my notes again

the answer is c.the valence of the atoms combine .

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.