Why does ice float on water?

• A. Because ice contains air bubbles that make it buoyant.
• B. Because the temperature of ice is lower than that of water.
• C. Because ice is heavier than water.
• D. Because the density of ice is less than that of liquid water.

Answer: (D)

Verified step by step guidance

1. Understand that whether an object floats or sinks in a liquid depends on its density relative to the density of the liquid. Density is defined as mass per unit volume, given by the formula \(\text{density} = \frac{\text{mass}}{\text{volume}}\).
2. Recognize that water expands when it freezes, meaning ice occupies a larger volume than the same mass of liquid water. This expansion causes the density of ice to decrease compared to liquid water.
3. Recall that the density of ice is approximately 0.92 g/cm³, while the density of liquid water at 4°C is about 1.00 g/cm³. Since ice has a lower density, it is less heavy per unit volume than water.
4. Apply the principle of buoyancy, which states that an object will float if it is less dense than the fluid it is placed in. Because ice is less dense, it displaces a volume of water equal to its weight before being fully submerged, causing it to float.
5. Conclude that the correct reason ice floats on water is due to its lower density compared to liquid water, not because of air bubbles, temperature differences, or weight.