A pond is cooled by winter air from 10 °C down to freezing. Which of the claims I to IV about how water's density behaves in this range are correct?

• I. Water has its maximum density at about 4 °C.
• II. When water is cooled from 4 °C to 0 °C, it contracts.
• III. A lake freezes from the top downward partly because water colder than 4 °C rises to the surface.
• IV. At 0 °C, ice is denser than liquid water.