Which of the following represents the prefix for one-millionth (10⁻⁶)?

The prefix that represents one-millionth (10⁻⁶) is "micro." In the metric system, prefixes are used to denote specific powers of ten. Each prefix corresponds to a specific multiplier that helps with easy representation and conversion of different measurements.

The prefix "micro" is widely recognized and used in various scientific contexts, including chemistry, biology, and physics. It is denoted by the Greek letter "µ" (mu). Therefore, when you see terms such as micrometer (µm) or microgram (µg), they refer to one-millionth of a meter and one-millionth of a gram, respectively.

Understanding metric prefixes is fundamental in scientific measurements, as they provide a clear and consistent way of expressing quantities that can vary widely in magnitude. In contrast, the prefixes like "nano" (10⁻⁹), "centi" (10⁻²), and "milli" (10⁻³) represent different fractions and do not correspond to one-millionth. This demonstrates the importance of knowing the appropriate prefixes when dealing with measurements and conversions in chemistry.