Question

when are parts per million and parts per billion used as measurements? when measuring concentrations that are exactly 50% when measuring concentrations that are larger than 100% when measuring concentrations that exceed 10% when measuring concentrations that are smaller than 1%

Explanation:

Parts per million (ppm) and parts per billion (ppb) are used for very dilute concentrations. Concentrations smaller than 1% (or 0.01 in decimal) are dilute, and ppm/ppb are suitable here. Other options: 50% is not dilute, >100% is impossible for concentration (max 100% for a component), and >10% is not dilute enough for ppm/ppb.

Answer:

When measuring concentrations that are smaller than 1%