Question: 2 ppm is equal to?
Answer: One liter (L) of pure water at 4ºC and 1 standard atmosphere pressure weighs exactly 1 kg, so 1 mg/L is 1 ppm, 2 mg/L is 2 ppm, 4 mg/L is 4 ppm, 10 mg/L is 10 ppm. Another way to say it is a liter of water weighs 1,000 grams or 1 million mil- ligrams.