Which weight corresponds to 1 millimeter of water?

• A. 0.5 gram
• B. 1 gram
• C. 1.5 gram
• D. 2 gram

Answer: (B)

The key idea is how mass relates to volume through density. Water has a density of about 1 gram per cubic centimeter, so 1 cubic centimeter of water weighs roughly 1 gram. If you imagine a layer of water that is 1 millimeter thick, the volume depends on the surface area it covers. For a surface area of 10 square centimeters, the volume is 10 cm^2 × 0.1 cm = 1 cm^3, which has a mass of about 1 gram. So, in that setup, 1 millimeter of water corresponds to around 1 gram. If the surface area were different, the mass would scale accordingly (smaller area means less mass, larger area means more mass).