Q. Which one of the following processes will produce hard water?
A) Saturation of water with $CaCO_{3}$
B) Saturation of water with $MgCO_{3}$
C) Saturation of water with $CaSO_{4}$
D) Addition of $Na_{2}SO_{4}$ to water
Explanation
(c)
Alkaline earth metal salts are causing hardness :
Temporary hardness caused by soluble Ca and Mg hydrogen carbonates. Calcium and magnesium soluble sulphates and chlorides cause permanent hardness.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.