Final answer:
The WHO standard for arsenic in drinking water is 10.0 mg/L, equivalent to 10 ppm. Since 1 ppm equals 1,000 ppb, the arsenic standard hence converts to 10,000 ppb.
Step-by-step explanation:
The World Health Organization (WHO) sets the drinking water standard for arsenic at 10.0 milligrams per liter (mg/L), which needs to be converted to parts per billion (ppb) for clarity of understanding. To convert from mg/L to ppb, we recognize that 1 mg/L is equivalent to 1 ppm since 'parts per million' refers to the ratio of the number of parts of a substance to a million parts of the total.
By understanding that 1 ppb is 1,000 times smaller than 1 ppm, the conversion is straightforward.
Therefore, to convert 10.0 mg/L (or 10 ppm) to ppb, we multiply by 1,000 (since 1 ppm equals 1,000 ppb), resulting in a standard of 10,000 ppb.