Which of the following statements are not correct? (i) F^(-) ion concentration above 2 ppm causes brown mottling in teeth. (ii) Excessive F^(-) (over 10 ppm) causes harmful effect to bones and teeth. (iii) Excessive lead in drinking water causes diseasemethemoglobinemia(iv) Deficiency of sulphate in drinking water causeslaxative effect

Which of the following statements are not correct? (i) F^(-) ion conc

1.	Which of the following statements are not correct? (i) F^(-) ion concentration above 2 ppm causes brown mottling in teeth. (ii) Excessive F^(-) (over 10 ppm) causes harmful effect to bones and teeth. (iii) Excessive lead in drinking water causes diseasemethemoglobinemia(iv) Deficiency of sulphate in drinking water causeslaxative effect
Answer» (II) and (iv) (ii) and (iii) (ii), (iii) and (iv) (iii) and (iv) Solution :For statement (iii), Methemoglobinemia (blue baby syndrome) is CAUSED due to excess of nitrate in drinking water. For statement (iv), Excessive SULPHATE (gt 500 ppm) in drinking water causes LAXATIVE effect, otherwise at moderate levels it is harmless