Soil Chemistry - Environmental Chemistry - Environmental Science & Engineering Previous Year Questions

Carbon cycle, nitrogen cycle and phosphorus cycle play important role in the ecosystems. Which of the following statement(s) is/are NOT correct about the phosphorus cycle?

Read the following statements
I. Trivalent chromium has relatively low aqueous solubility, and low mobility in the soil environment. By contrast, hexavalent chromium has a higher aqueous solubility and greater mobility in the soil environment.
II. The chemical reaction between trivalent chromium and zero-valent iron will result in transformed version called hexavalent chromium.
III. Hexavalent chromium is a known carcinogen.
IV. Trivalent chromium has relatively higher human toxicity as compared to hexavalent chromium.
The correct choice is