Which option is the expansion for the unit Parts Per Billion?

Which option is the expansion for the unit Parts Per Billion?

• A. Parts Per Million
• B. Parts Per Thousand
• C. Parts Per Billion
• D. Parts Per Basin

Answer: (C)

The main idea here is understanding what the abbreviation ppb stands for. ppb is the abbreviation for Parts Per Billion, so the expansion of the unit Parts Per Billion is simply Parts Per Billion. This unit expresses extremely small concentrations—one part in a billion parts of the mixture. In water measurements, 1 ppb is often about 1 microgram per liter, and it sits well below 1 part per million (ppm), since 1 ppm equals 1000 ppb. The other options aren’t correct because they refer to different, standard units (ppm, per thousand) or are not recognized units at all.

The main idea here is understanding what the abbreviation ppb stands for. ppb is the abbreviation for Parts Per Billion, so the expansion of the unit Parts Per Billion is simply Parts Per Billion. This unit expresses extremely small concentrations—one part in a billion parts of the mixture. In water measurements, 1 ppb is often about 1 microgram per liter, and it sits well below 1 part per million (ppm), since 1 ppm equals 1000 ppb. The other options aren’t correct because they refer to different, standard units (ppm, per thousand) or are not recognized units at all.