It needs energy to keep it going. An example is cooking. It keeps going after it is started. An example is a fire. They are usually produced in nuclear reactions.
All solutions are homogeneous.
This bond is ten times weaker than the covalent bond, and ten times stronger than the van der waals force. The hydrogen bond caused water to have its unusual properties of high boiling point, high melting point, high surface tension, and its formation of the six- sided ring structure in ice. The latter causes water to expand upon freezing, become less dense, and float in water. TOP ION is a charged atom or group of atoms. Ionization is caused by a gain or loss of electrons.