Lead is a heavy metal that is present in drinking water in specific small amounts. The maximum amount of lead allowed in drinking water in parts per million is 15 ppm. Thus, option A is correct.
Parts per million (ppm) is the unit of expressing the mass of the substance with respect to the volume of the solution. It is generally used to represent the concentration of the contaminants or chemicals.
Given,
Mass of lead (Pb) = 15 mg
Volume/mass of water = 1 kilogram
The concentration of lead is calculated as,
Mass of Lead x 10⁶ ÷ Mass of water
=15 × 10⁶ ÷ 1000000
= 15 mg/kg
As it is known that 1 ppm = 1 mg/Kg
So, 15 mg/kg = 15 ppm
Therefore, option A. the maximum level of lead allowed in drinking water is 15 ppm.
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Your question is incomplete, but most probably your full question was, The maximum level of lead allowed in drinking water is 15 mg/kg. What is this concentration in units of parts per million?
