Me .

why does earth rotate?

a.)because earth is formed from cold gases collapsing due to gravity

b.)because the matter in the nebula that formed earth was spinning

c.)because earth forms more than 99% of the mass of the solar system

d.)because the hydrogen atoms inside the nebula fused to form helium

I think it's B but I'm not 100% sure srry if I'm wrong

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.

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.