Answer:
it is good for thermoelectric power plant cooling
it means that there is a lot of salt in the water
Someone would remove salt from water to be able to drink it
lastly, salt can be removed from water with reverse osmosis systems
Mg gained mass because it went from being a single element (on the reactant side) to being a molecule (on the product side).
Technically there is only one phase unless you account for a solution where you have a pure liquid with something dissolved in it. Unless you count aqueous as a phase which is just dissolved. Since you are in high school the answer you are looking for is one. <span />