The maximum contaminant level (mcl) set by the epa of cadmium in drinking water is 0.0050 mg/l . convert the mcl of cadmium from milligrams per liter to parts per billion (ppb).

5 ppb of Cd

Explanation:

Given , Concentration = 0.0050 mg/L

To find this concentration in parts per billion

As,

1 mg per liter = 1 ppm

Parts per billion is defined as the number of the units of the mass of contaminant per thousand million units of the total mass. The relation between ppm and ppb is shown below as:

1 ppm = 1000 ppb

Concluding as:

1 mg per liter = 1000 ppb

So,

0.0050 mg/L = 1000 × 0.0050 ppb = 5 ppb of Cd

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.

the correct answer would be d. hope this !