How many of the following in drinking water below 30 ppm do not cause any effect on the body as per international standards of water? Pb^(2+),Hg^(2+),Mn^(2+),Cd^(2+),Cl^(-),NO_(3)^(-),SO_(4)^(2),Ca^(2+),Mg^(2+)

How many of the following in drinking water below 30 ppm do not cause

1.	How many of the following in drinking water below 30 ppm do not cause any effect on the body as per international standards of water? Pb^(2+),Hg^(2+),Mn^(2+),Cd^(2+),Cl^(-),NO_(3)^(-),SO_(4)^(2),Ca^(2+),Mg^(2+)
Answer» 5 2 3 6 Answer :A