Define the concentration measurements of parts per million

Explanation:

Parts per million (ppm) is the number of units of mass of a contaminant per million units of total mass

ppm (or ppmm) is used to measure the concentration of a contaminant in soils and sediments. In that case 1 ppm equals 1 mg of substance per kg of solid (mg/kg).

fire could start, buildings collapsing, and ash falling from the sky.

explanation:

this is because the buildings or plants could catch on fire and the buildings would most likely collapse. lastly ash would fall because all the burning would cause ash to fall from the sky.

hope this .

c is the answer because when something is left after something evaporates that shows the chemical change.