Hard water contains calcium and magnesium, which undergo oxidation and
clog water pipes. which statement best describes this change as a chemical change?

calcium and magnesium dissolve in water.

calcium and magnesium evaporate on contact with the walls of the pipe.

calcium and magnesium form precipitates of their respective oxides.

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

What is the mass of 0.46 mol of mgcl2

According to the diagram, what sources contribute to the phosphorus found in soil? according to the diagram, phosphorus found in soil contributes phosphorus to what other sources?