True or False: NH4+ is the only acid-forming ion.

The statement that NH4+ is the only acid-forming ion is false because there are other ions that can also lead to acidity in the soil. While ammonium (NH4+) does contribute to soil acidification as it is converted to nitrate (NO3-) in a process that releases hydrogen ions (H+), several other ions and processes can also result in acid formation.

For example, sulfuric acid (H2SO4) and nitric acid (HNO3) derived from the oxidation of sulfur and nitrogen compounds, respectively, are known acid-forming entities as well. Additionally, the application of fertilizers containing sulfur and their subsequent conversion to sulfate (SO4 2-) can also contribute to soil acidity.

Therefore, stating that NH4+ is the only acid-forming ion is incorrect because it overlooks the existence of other chemical processes that contribute to soil acidity, making the correct response false.