Which of the following equations represents the reaction leading to the removal of permanent hardness of water?
A. \(\mathrm{MgSO}_{2}+\mathrm{Na}_{2} \mathrm{CO}_{3} \quad \mathrm{MgCO}_{3}+\mathrm{Na}_{2} \mathrm{SO}_{4}\)
B. \(\mathrm{Ca}(\mathrm{OH})_{2}+2 \mathrm{HCl} \quad \mathrm{CaCl}_{2}+2 \mathrm{H}_{2} \mathrm{O}\)
C. \(\mathrm{Ca}\left(\mathrm{HCO}_{3} h_{2}+\mathrm{Ca}(\mathrm{OH})_{2} \quad 2 \mathrm{CaCO}_{2}+2 \mathrm{H}_{2} \mathrm{O} \quad\right.\)
D. \(\mathrm{MgSO}_{4}+\mathrm{BaCl}_{2} \quad \mathrm{MgCl}_{2}+\mathrm{BaSO}_{4}\)
Correct Answer: A
