Matter can change from one state to another when thermal energy is absorbed or released. A great example is Ice having its state changed to the liquid that is WATER. When ice is heated, it absorbs thermal energy and its temperature rises. At some point, the temperature stops rising and the ice begins to change to water, a liquid. As we all know, The change from the solid state to the liquid state is called melting.
Not sure but i think cohesion forces
This is because the traits like height, are influenced by environmental conditions around the individual. For example, there are two children born to same mother. But one is given best facilities, nutrition and care, whereas other one is brought up by a poor family, which hardly get good food to eat. His condition is much worse than the first case. In such a situation, the former child will grow up healthy and fit, and will have more height than the later one. Although, both got genes from same parent, but the environmental conditions influenced the expression of those genes differently.