GATE 2017 CE (CE2) – Question 63
Water ion data are (milligram equivalent; concentration mg/L): Ca²⁺ (20;60), Mg²⁺ (12.2;36.6), Na⁺ (23;92), K⁺ (39.1;78.2), Cl⁻ (35.5;71), SO₄²⁻ (48;72), HCO₃⁻ (61;122). Total hardness expressed as CaCO₃ is ______ mg/L.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 300 to 300
Explanation
Calcium contributes $60/20=3$ meq/L and magnesium $36.6/12.2=3$ meq/L. Total hardness is $(3+3)50=300$ mg/L as CaCO₃. Sodium and potassium do not contribute to hardness.