Answer: 1 milligram (mg) is equal to 0.001 milliliters (mL) for water at standard temperature and pressure.
Explanation: The conversion between milligrams and milliliters depends on the density of the substance. For water, the density is 1 g/mL, meaning 1 g (1000 mg) occupies 1 mL. Therefore, to convert milligrams to milliliters for water, you divide by 1000.