Question

100 kg of a sample of water contained 60g of $MgS{O}_4$ the degree of hardness is:

• A. 6 ppm
• B. 60 ppm
• C. 5 ppm
• D. 500 ppm

Answer 1

The correct option is D 500 ppm

${10}^5$ gms of a sample of water contain 60 gms of $Mg{SO}_4$

${10}^6$ gms of sample of water contain $\frac{60}{{10}^5}\times {10}^6$ = 600 gms of $Mg{SO}_4$

120 gms of $Mg{SO}_4$ has hardness = 100 ppm

600 gms of $Mg{SO}_4$ has hardness = $\frac{100}{120}\times 600$ = 500 ppm