NEET Chemistry Hydrogen Questions Solved


A sample of hard water was found to contain 68 ppm of CaSO4 and 19 ppm of MgCl2. Its total hardness is –

(A) 70 ppm                             

(B) 50 ppm

(C) 20 ppm                             

(D) 100 ppm

(A). 136 ppm CaSO4 = 100 ppm CaCO3 = 95 ppm MgCl2.

       Thus 68 ppm CaSO4 = 100 × 68 / 136 = 50 ppm CaCO3.

       19 ppm MgCl2 = 100 × 19/95 = 20 ppm CaCO3.

       Total hardness = 50 + 20 = 70 ppm

Difficulty Level:

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