A student is provided with a sample of iron pyrite and a sample of gold. Suggest how the student could distinguish between the two substances

Iknow #2 is d. i just need to know why

The boiling point of propanoic acid is higher than that of 1-butanol because: propanoic acid has a higher molecular weight than 1-butanol. propanoic acid is more soluble in water than 1-butanol. propanoic acid is a better hydrogen bond donor than 1-butanol. propanoic acid forms hydrogen bonded dimers and 1-butanol does not. 1-butanol forms hydrogen bonded dimers and propanoic acid does not.

How many valence electrons are in atom of radon?