Temporary hardness can be dealt with using boiling water(Calcium hydrogen carbonate) but Permanent won't so you need to use washing soda instead(sodium carbonate) or Ion exchange resin
I think the answer is c but I’m not sure
1.) when components are needed to be used in different ways
2.) sublimation, filtration, evaporation, and distillation
It would be an electronic charge of +2 because there are 4 protons and 2 electrons