Examples of hard water​

lake water, swamp water, like, any dirty and unpurified forms of water is hard water

Explanation:

Water is considered hard when it contains a large amount of the cations (positively-charged ions) Ca2+, Mg2+, and/or Fe3+. These ions are typically introduced into a water supply when the water drips through a mineral. Limestone is an example of a mineral that contains a source of calcium.

Explanation:

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.