Question

Indicate whether the following samples of matter is a heterogeneous mixture, a homogeneous mixture, a compound, or an element.

a. a blue-colored, single-phase liquid that when boiled away (evaporated) leaves behind a solid residue

b. a "cloudy" liquid that separates into two layers upon standing overnight 

c. a non-uniform, white crystalline substance, part of which dissolved in alcohol and part of which does not dissolve in alcohol

d. a colorless gas that cannot be separated into simpler substances using physical means and that reacts with metal magnesium to produce both magnesium-oxygen compound and a magnesium-nitrogen compound