Final answer:
Soft water has had impurities, such as calcium, magnesium, and other metal ions, removed. This is achieved through processes such as lime softening or ion exchange.
Step-by-step explanation:
Soft water has had impurities, such as calcium, magnesium, and other metal ions, removed. Soft water is achieved through processes such as lime softening or ion exchange. Lime softening involves adding calcium hydroxide to hard water, which causes calcium and magnesium to precipitate and be filtered out. Ion exchange involves replacing the unwanted ions in hard water with more acceptable ions through a resin-containing column. Both processes result in water that is free from impurities.