__________ is not a fertiliser.

ANS:B - Ferrous sulphate

Ferrous sulfate, also known as iron(II) sulfate, is a chemical compound with the formula FeSO4. It is composed of iron (Fe) and sulfate (SO4) ions and exists in several hydrated forms, with the most common being ferrous sulfate heptahydrate (FeSO4·7H2O), which is a blue-green crystalline solid. Here's an explanation of ferrous sulfate and its various uses:

1. Industrial Production: Ferrous sulfate is primarily produced as a byproduct of various industrial processes, particularly the production of titanium dioxide pigment and the pickling of steel. It can also be synthesized directly from iron and sulfuric acid.
2. Fertilizer: Ferrous sulfate is commonly used as a soil amendment and fertilizer in agriculture and horticulture. It is applied to the soil to correct iron deficiencies in plants, which can manifest as chlorosis (yellowing of leaves) due to insufficient iron uptake. Ferrous sulfate provides a readily available source of iron that plants can absorb and utilize for chlorophyll synthesis and other metabolic processes.
3. Algae Control: Ferrous sulfate is sometimes used as an algaecide and water treatment agent to control algae growth in ponds, lakes, and water bodies. It works by precipitating phosphates from the water, which are essential nutrients for algae growth. By reducing phosphate levels, ferrous sulfate helps inhibit the growth of algae and improve water quality.
4. Medical Use: In medicine, ferrous sulfate is used as an iron supplement to treat iron deficiency anemia, a condition characterized by low levels of iron in the blood. Iron is an essential mineral for the production of hemoglobin, the oxygen-carrying protein in red blood cells. Ferrous sulfate provides a source of elemental iron that can be absorbed by the body to replenish iron stores and alleviate symptoms of anemia.
5. Water Treatment: Ferrous sulfate is employed in water treatment processes to remove hydrogen sulfide (H2S) gas and reduce odors in wastewater and sewage systems. It reacts with hydrogen sulfide to form insoluble iron sulfide precipitates, which can then be removed through filtration or sedimentation.
6. Other Uses: Ferrous sulfate has various other industrial applications, including as a reducing agent in chemical synthesis, a mordant in textile dyeing, and a colorant in pigments and inks. It is also used in the production of iron oxide pigments, inks, and magnetic recording media.

Overall, ferrous sulfate is a versatile compound with diverse applications in agriculture, water treatment, medicine, and industry. Its role as a soil amendment, fertilizer, and iron supplement makes it an important component in maintaining plant health and addressing iron deficiency-related issues in both agricultural and medical contexts.