Answer:
208 mg/L
Explanation:
Only Mg++ and Ca++ causes hardness not Na+
Given
Mg++ = 20 mg/L
Ca++ = 50 mg/L
[tex]Hardness\ of\ water = C^{2+}\times \frac{equivalent\ weight\ of\ CaCO3}{equivalent\ mass\ of\ C^{2+}}\ +\ mg^{2+}\times \frac{equivalent\ weight\ of\ CaCO3}{equivalent\ mass\ of\ mg^{2+}}[/tex]
= [tex]50\times\frac{50}{20}\ +\ 20\times\frac{50}{12}[/tex]
= 208.33 mg/L [tex]\approx[/tex] 208mg/L
