What is "what factor is most important in determining whether water is a solid?

The most important factor in determining whether water is a solid is its temperature. Water freezes into a solid state at 0 degrees Celsius (32 degrees Fahrenheit). When the temperature of water drops below this point, the molecules within the water slow down and come together to form a solid structure, commonly known as ice. The molecules are held together by strong hydrogen bonds, which give ice its solid and rigid form. Therefore, temperature is the key factor in determining whether water will exist as a solid.