Question

A number of minerals like Ca, Mg and K are held over the surface of clay particles because the latter are
A. Negatively charged
B. Positively charged
C. Neutral
D. Having both positive and negative residual valances

Answer 1

Hint: All these three minerals i.e. Ca, Mg and K possess positive charge, or we can say that they are cations. On other hand clay particles possess negative charge. This is the reason by which these three minerals are attracted towards the clay particles and get attached to it with a strong bond.

Complete answer:
Ca, Mg and K as mentioned above are positively charged or cations. In their ionic state they have similar charge, K is missing one electron or monovalent whereas Ca and Mg are missing two electrons so are divalent cations. The relationship between these three minerals are not only important for plant growth but their imbalance can even disturb the plant growth and can cause certain deficiencies, their balance is required to avoid antagonism induced deficiencies in plants for maintaining their health and good productivity.

Hence the correct answer is (A) Negatively charged.

Note: Antagonism occurs when excessive concentration of one nutrient inhibits the uptake of another nutrient. Three of them are important for the plant in different ways. Calcium is an important component of cell wall; it helps in cell growth and allows permeability of the cell wall and also it participates in translocation of nutrients and carbohydrates within the plants. Magnesium is an important component for chlorophyll due to which photosynthesis occurs, it also helps in protein synthesis and responsible for transfer of energy within the cell. Potassium exists as a component of several soil minerals; it is held into the cations exchange capacity lastly the soil solution contains potassium that is readily available for plants.