Which is a reactive metal? ? a.) silicon b.)sodium c.)chorine d.)argon

b. sodium is a reactive metal because it has one electron in the outermost electron shell and it gives up one electron to another element.

The answer would be B.) Sodium, because, "As a part of the alkali metal group in the periodic table, sodium is highly reactive and is never found pure in nature. It tarnishes easily and has a low melting point and density. ... Within the alkali metals, sodium is more reactive than lithium but less reactive than potassium."

(https://chem.libretexts.org/...Metals/Z%3D011_Chemistry_of_Sodium_(Z%3D11))

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

answer; natural resources;