If two equal volumes contain water and ice, which weighs more?

If two equal volumes contain water and ice, which weighs more?

• A. Water
• B. Ice
• C. They weigh the same
• D. Depends on temperature

Answer: (A)

The key idea is density: mass per unit volume. With equal volumes, the heavier one is the one with higher density. Ice is less dense than liquid water because it forms an open crystal structure that makes it expand when it freezes. Water, in its liquid form, is more tightly packed. Numerically, water is about 1.0 g/cm³ while ice is about 0.92 g/cm³, so the same amount of space contains more mass of water than of ice. Hence, the water weighs more. (If you compared equal masses, they’d weigh the same, but the question fixes volume, not mass.)

The key idea is density: mass per unit volume. With equal volumes, the heavier one is the one with higher density. Ice is less dense than liquid water because it forms an open crystal structure that makes it expand when it freezes. Water, in its liquid form, is more tightly packed. Numerically, water is about 1.0 g/cm³ while ice is about 0.92 g/cm³, so the same amount of space contains more mass of water than of ice. Hence, the water weighs more. (If you compared equal masses, they’d weigh the same, but the question fixes volume, not mass.)