Which of the following is equivalent to 1 × 10-3 g?

To understand why the correct answer is 1 milligram, we must first interpret what 1 × 10^-3 g means. This notation is in scientific form, where 10^-3 indicates that we divide 1 gram by 1000. Therefore, 1 × 10^-3 g is equivalent to 0.001 grams.

Next, we need to recognize the metric prefixes associated with these units of mass. One milligram (mg) is defined as one-thousandth of a gram. Therefore, 1 milligram is equal to 0.001 grams, which confirms that 1 × 10^-3 g is indeed equivalent to 1 milligram.

This understanding ties back to the metric system, where prefixes like "milli-" denote a factor of 10^-3, linking grams, milligrams, and micrograms in a clear hierarchy. This establishes a clear and precise way to convert between different measurements of mass.

In contrast, the other options do not accurately reflect the same mass as 1 × 10^-3 g; for instance, 0.0001 gram is much smaller than 1 milligram, and 1 kilogram is 1000 grams, significantly larger than the specified mass.