Natural abundance of oxygen I think
It was concluded that different liquids do evaporate at different rates, according to the physical properties of the given substance. Nail polish remover vaporized the quickest, followed by water, salt water, vinegar, orange juice and oil.
C.) A metal and a non-metal
White gold is yellow gold that has had other alloys added to it to make it appear white. New polished white gold has a bright white metal color. Depending of the type of alloys used in the fabrication of white gold, white gold jewelry tends to have a faint yellowish tint with wear.