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`. The molar concentration of `AgNO_(3)` solution if one drop of `AgNO_(3)` measure `0.05 mL` is:A. `6.04xx10^(-3)M`B. `7.04xx10^(-3)M`C. `150 M`D. `3.52 M`