What causes a substance to change states of matter?
Energy causes a substance to change states of matter. A matter needs energy to melt, evaporate, boil. Remember: Energy has a sudden change, but the temperature remains absolutely the same. An example of a change in energy is when ice is melting.
Qualitative properties are properties that are observed and can generally not be measured with a numerical result. They are contrasted to quantitative properties which have numerical characteristics.
