Q. Permanent hardness can be removed by adding
A) $Cl_{2}$
B) $Na_{2}CO_{3}$
C) $Ca\ (OCl)\ Cl$
D) $K_{2}CO_{3}$
Explanation
(b)
Permanent hardness is removed by precipitating carbonates of $Ca^{2 +}\ and\ Mg^{2 +}.$
$\ \ \ \ \ \ CaCl_{2} + \ Na_{2}CO_{3} \rightarrow CaCO_{3} \downarrow + 2NaCl$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.