Which choice can be a solid, liquid, or a gas?

a. steel

b. silver

c. water

d. carbon dioxide

I believe that your option C would be the correct answer. We know that water can turn to a solid materail because during cold temperatures, water turns to ice.

We know that water can turn to gas, as water can evaporate.

And also, we know that water is obviosly a liquid.

Therefore, Option C would be your answer.

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.