Which of the following samples of water would have the greatest density?

• A. Water vapor at 100 °C
• B. Liquid water at 25 °C
• C. Liquid water at 4 °C
• D. Ice at 0 °C

Answer: (C)

Verified step by step guidance

1. Understand that density is defined as mass per unit volume, given by the formula \(\rho = \frac{m}{V}\), where \(\rho\) is density, \(m\) is mass, and \(V\) is volume.
2. Recognize that the density of water varies with its physical state (solid, liquid, gas) and temperature because temperature affects the volume of the substance.
3. Recall that water is most dense at approximately 4 °C in its liquid state, which is a unique property due to hydrogen bonding causing water to expand upon freezing and also to contract until 4 °C.
4. Compare the densities qualitatively: water vapor at 100 °C is a gas and has much lower density than liquid water; liquid water at 25 °C is less dense than at 4 °C; ice at 0 °C is solid but less dense than liquid water because ice has an open crystalline structure.
5. Conclude that among the given options, liquid water at 4 °C has the greatest density due to its molecular arrangement and temperature-dependent volume.