The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be 1000 ppb , 40 ppb , 100 ppm and 0 . 2 ppm , respectively. This water is unsuitable for drinking due to high concentration of:

Step-by-step solution

Parameters Maximum prescribed concentration in drinking water Iron 0 . 2   ppm Fluroide   1 . 5   ppm Lead 50   ppb Nitrate 50   ppm Hence the concentration of nitrate in a given water sample exceeds from the upper limit as given above.