If your science teacher says B, it’s probably because water has a negative and positive end, heat is just a form of energy, as other atoms can’t leave (they’re attracted to the ends) they are being insulated; but notice that ice will melt into gas (where atoms have tons of space) for other atoms to escape. Hence ice and gas aren’t ideal. (Air is a gas here.)
It’s not a 100% but hopefully it helps with some kind of analogy.
Answer: Some are solid, some are gaseous, a few are liquid. Some are metallic: they have a peculiar lustre; some are coloured (like sulfur) or colourless. Some have a low density; some have a high density. Some are malleable and ductile; some are brittle. Some conduct electricity and heat well; some don’t.
Many metals tend to have structural uses. Nonmetallic elements less so.
Metals tend to have crystal forms featuring close-packed centro-symmetrical structures. Nonmetallic elements tend to have crystal structures featuring more open and directionally packed structures.
Some are especially toxic; some are essential to life; some are both depending on exposure level.
Most are stable; some are less so.
Some elements are highly reactive; some are almost inert (helium, neon, and argon may be completely inert in ambient conditions).
Many metals have basic oxides; quite a few oxides of nonmetallic elements form acids when they are dissolved in water. Some elements can go both ways.
There are many generalisations you can make about metallic and nonmetallic elements, and quite a few exceptions at the margins.
Explanation:
Molarity is mole divided by volume in litres.
0.5mol divide by 0.5L = 1M