Passage I

Two artificial marshes were built to help reduce the amounts of iron and manganese in, and the acidity of, water seeping into a stream from a coal mine site (see Figure 1). Table 1 shows precipitation, in centimeters (cm); flow rate, in liters per minute (L/min); pH (acidity); and iron and manganese content, in milligrams per liter (mg/L), of inlet and outlet water over 5 days.

Water having a higher level of iron or manganese or a lower pH than the values given in Table 2 is said to be contaminated.

4. According to the information provided in Tables 1 and 2, on any given day, the water leaving the marshes at Outlet 2 is contaminated with respect to:

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

Corresponding to table 1, the minimum pH of Outlet 2 in 5 days is 6.4, which is higher than 6.0 and does not exceed the standard;

The maximum concentration of Iron is 22.7, which exceeds the 3.5 given in table 2;< /p>

The maximum concentration of Mn is 6.4, which exceeds the 2.0 given in table 2, so it also exceeds the standard