# The domestic water supply is treated by bleaching powder to remove unhygienic species in water and to make it safe for drinking water. However, this g

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The domestic water supply is treated by bleaching powder to remove unhygienic species in water and to make it safe for drinking water. However, this given rise to Ca^(2+) and Cl^(-) ion contamination in water. Both these ions are also injurious for health if a minimum concentration is crossed. The chloride ions are tested by a kit provided by many companies having AgNO_(3) solution that is added drop by drop to 23 mL of water sample to which an indicator has been added. When sufficient silver nitrate is added to remove Cl^(-1) ions as AgCl solid, the solid turns orange. The colour change is noticed by addition of AgNO_(3) having molar concentration such that each drop (0.05 mL) of AgNO_(3) converts 12.5 mg of Cl^(-) ions AgCl.
Assuming that concentration of Ca^(2+) ions in solution is equal equivalence ratio to chloride ions, the hardness of water is:
A. 9.185xx10^(3)"ppm"
B. 6.185xx10^(3)"ppm"
C. 1.185xx10^(3)"ppm"
D. 4.185xx10^(3)"ppm"

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Eq. of CaCO_(3)="Eq.of" Ca^(2+)= "Eq.of" Cl^(-)
( for 1 "litre" water)
(w)/(100//2)=0.1837
w_(CaCO_(3))=(0.1837xx100)/(2)=9.185 g
therefore Hardness =(9.185xx10^(6))/(10^(3))
9.185xx10^(3)"ppm"