Why is iron described as an element

The most efficient way to establish the best possible economizer position is to measure

As light moves from one material into the next, which of the following affects how much the light waves will refract, or bend? angle at which the ray strikes the medium color of the material density of the material temperature of the light wave

Using the periodic table, complete the following. element: hydrogen symbol: h₂ molecular weight: g mass of one mole: g/mol