Which two units are equivalent for measuring small volumes?

• A. Liters and milliliters
• B. Kilograms and grams
• C. Milliliters and cubic centimeters
• D. Liters and cubic centimeters

Answer: (C)

The key idea is that two units are equivalent when they measure the same amount of a quantity. For small volumes, milliliters and cubic centimeters are defined to be the same size: 1 milliliter equals 1 cubic centimeter. This means they describe the same amount of liquid, and you can use either unit interchangeably in many practical situations. For example, 5 milliliters is the same volume as 5 cubic centimeters.

The other pairs don’t fit as equivalents for measuring small volumes: kilograms and grams measure mass, not volume; liters and milliliters are both volume units but differ in size (1 liter equals 1000 milliliters); liters and cubic centimeters are related by a factor as well (1 liter equals 1000 cubic centimeters), so they’re not the same amount.