What is the physical state of water at -24 degrees?

Answer 1

Solid.

Answer 2

If the water is in thermal equilibrium with the surroundings, than the water would be completely frozen solid, and would be ice. However, often things are not in perfect equilibrium with their surroundings (some things can take thousands of years to reach equilibrium!). For instance, imagine you fill up your ice cube trays with water, and put them in the freezer. The trays will still have liquid water in them even after you've put them in a freezer at -2 °C (even if the freezer was at -50 °C!). Ice cubes take a while to form in your freezer mostly because it takes a while for the water to reach thermal equilibrium with the cold air inside the freezer. The more water you put in the freezer, the longer it takes to reach equilibrium. The colder the freezer, the faster the water will freeze (although it won't reach equilibrium any faster in this case). Another example is the ocean. Even on a scorching hot day, when the air temperature is extremely hot, the temperature of the water in the ocean does not change so much, and is typically much cooler than the air temperature. That is because the ocean temperature is not in fast thermal equilibrium with the air temperature. The air temperature can change much much faster than the water temperature. This has to do with the vast size of the ocean, but also because of the properties of water (water has a much higher heat capacity than air). So even though the ocean is exposed to the hot air, the ocean stays cool because they are not in thermal equilibrium. If the air stayed hot enough constantly for a long time (and I mean a very long time -- many years), the oceans would start to warm up. This is one of the major effects of global warming in fact (and a very serious one too).

Answer 3

Ice (solid), since the freezing point is 0C