The law of conservation of mass states that mass is neither created nor destroyed by chemical reactions or physical transformations. according to this, the mass of the products must equal the mass of the reactants.
The water from the ocean gets evaporated by the sun and travels as a gas into the clouds. As more and more water builds up in the clouds it will eventually rain or snow
Natural disasters because they are all natural
Due to extreme (too much) cell division, a mutation of cells will occur and that is the cancer within humans.