Ppm is used to describe very small amounts of substance?

parts per million (ppm), parts per billion (ppb) and parts per trillion (ppt) are the most commonly used terms to describe very small amounts of substances. a ppm of a chemical in water means that, in a million units of water, there would only be one unit of the chemical.

1 a

2 d

3 a

4 c

explanation:

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.