Which two substances are the main elements that make hard water?Group of answer choicesCalciumMagnesiumSodium

What is hard water? What compounds are in water to make it hard?

Hydrogen and what other substance is known to form water?Group of answer choicesoxygenheliumsiliconenirogen

What is the second most common ion in the seawater?Group of answer choiceschloridemagnesiumoxygensodiumcalcium

You want to test for hardness of water but hard water is not available inthe laboratory. Which of the following compounds may be dissolved inpure water to make it hard ?(i) Hydrogen Carbonate of Sodium(ii) Sulphate of Magnesium(iii) Chloride of Calcium(iv) Carbonate of Sodium

Which one of the following elements will remain as liquid inside pure boiling water ?