Question 17How is a mass of 10⁻⁶ kilogram correctly written?1 mg, one milligram✓Correct answer1 µg, one microgram1 µkg, one microkilogram1 mkg, one millikilogramExplanationTwo prefixes may never be stacked, so you cannot add micro to the kilo that is already inside 'kilogram'. Prefixes for mass are attached to the gram instead, which makes 10⁻⁶ kilogram equal to one milligram.