Q1: Which one of the following is used as a nitrogenous fertiliser, as a weed killer in the onion fields and for correcting acidic soils ?

ANS:D - Calcium cyanamide

Calcium cyanamide, with the chemical formula CaCN2, is an inorganic compound that is primarily used as a nitrogen fertilizer. It is produced by reacting calcium carbide with nitrogen gas at high temperatures. The reaction proceeds as follows: CaC2+N2→CaCN2+CCaC2​+N2​→CaCN2​+C Calcium cyanamide is a grayish-white solid that is soluble in water. It releases ammonia and calcium carbonate when hydrolyzed in water: CaCN2+3H2O→Ca(OH)2+2NH3CaCN2​+3H2​O→Ca(OH)2​+2NH3​ This hydrolysis reaction makes calcium cyanamide an effective nitrogen fertilizer because it provides a slow and steady release of ammonia, which serves as a nitrogen source for plants. Additionally, the hydrolysis reaction also results in the formation of calcium hydroxide (Ca(OH)2Ca(OH)2​), which can help to neutralize soil acidity, making it useful for correcting acidic soils. Besides its role as a fertilizer, calcium cyanamide has other applications as well:

1. Weed Control: Calcium cyanamide can act as a herbicide due to its ability to inhibit seed germination and root growth of weeds. It disrupts the plant's cellular respiration process, leading to its death.
2. Soil Conditioning: Apart from neutralizing soil acidity, calcium cyanamide can also improve soil structure and enhance microbial activity, leading to better soil health and crop productivity.
3. Industrial Applications: Calcium cyanamide is used in some industrial processes, including the production of cyanide compounds and as a precursor for the synthesis of organic compounds.