Borildls03 36. Two metallic ions commonly present in hard water
a. catwo metallic ions commonly present in hard water ​

Mg2+ and Ca2+

Explanation:

Hard water are water that happen to contain salts of calcium and magnesium ions. They can occur as chlorides, sulphates, bicarbonates etc. Hard water wastes soap as it requires an above normal amount to form lathers.

The metallic ions are;

Mg2+ and Ca2+

a boiling water reactor does not boil the water. a pressurized water reactor boils the water faster. a pressurized water reactor is heated directly by the core. a pressurized water reactor does not use fission.

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.