Which of the following correctly fills in the blank? 1 gram = ______ kilogram.…

The metric prefix “kilo” means 1000, so 1 kilogram equals 1000 grams. Converting a quantity from grams to kilograms means dividing the gram value by 1000, and dividing by 1000 is the same as multiplying by 10-3 — so the result can be written either as the fraction 1/1000 or in exponential form as 10-3.

1. 1 kilogram = 1000 grams, so 1 gram = 1 ÷ 1000 kilogram.

2. 1 ÷ 1000 kilogram is written as the fraction 1/1000 kg.

3. Since 1/1000 = 1/103 = 10-3, the same quantity in exponential form is 10-3 kg.

4. Checking the remaining values: 0.0001 kg equals 1/10,000 kg — ten times smaller than 1/1000 kg — so it is not this conversion; and 1000 kg comes from applying the ×1000 step that is actually used when converting kilograms to grams, but incorrectly keeping the unit written as kilograms instead of switching it to grams — the wrong operation paired with the wrong unit for what is asked here.

Multiplying back confirms it: 1/1000 kg × 1000 = 1 gram, and 10-3 kg × 1000 = 1 gram — both consistent. But 0.0001 kg × 1000 = 0.1 gram and 1000 kg × 1000 = 1,000,000 grams — neither equals the original 1 gram, ruling those two out.

So the pairing that correctly fills the blank lists 1/1000 kg together with 10-3 kg.