- Physical Sciences
SystÃ¨me International dâUnitÃ©s. Internationally agreed coherent system of units: distance in metre (m), mass in kilogram (kg), time in second (s), current strength in ampere (A), temperature in kelvin (K), quantity of a substance in mole (mol) and strength of light in candela (cd) etc.
during a reaction a molecule reacts with water to form ions (to separate into ions).
one reactant loses electrons and another gains electrons
the natural circulation of water on, above or below the surface of the Earth.