Calcium carbide powder which is used for artificial ripening of fruits, produces :

Question

Accepted Answer

The correct option is 4: Acetylene

Calcium carbide (CaC2) is the substance traditionally, though illegally in many jurisdictions, employed for the artificial ripening of fruits. The crucial fact to understand is that the ripening effect is not caused by the solid powder itself, but by the gas it releases when it reacts with ambient moisture, such as the humidity in the air or water droplets on the fruit's surface. This chemical reaction is the hydrolysis of calcium carbide, which yields calcium hydroxide and Acetylene gas: CaC2 + 2H2O -> Ca(OH)2 + C2H2 (Acetylene). Acetylene (C2H2) is a hydrocarbon gas that possesses a structural and functional similarity to Ethylene (C2H4), which is the natural ripening hormone. Due to this similarity, Acetylene can effectively bind to the Ethylene receptors on the fruit cells, thus successfully mimicking the action of the natural hormone and forcefully initiating the biological processes of ripening, including the breakdown of starches into sugars, color changes, and softening. The direct chemical product of the carbide powder that triggers this artificial ripening is unequivocally Acetylene.

The incorrect option is 1: Jasmonic acid

Jasmonic acid is fundamentally recognized as a plant defense hormone, not a primary agent for fruit ripening. Its primary biological functions revolve around mediating plant responses to various environmental stresses, such as wounding and defense against herbivorous insects and microbial pathogens. While it plays a role in complex, internal signaling pathways and is involved in developmental processes like flower senescence, it is not the volatile gaseous signal responsible for controlling the final stage of fruit maturation. Applying Jasmonic acid would primarily gear the plant toward a stress response, which is conceptually opposite to the physiological goal of rapid, quality-controlled ripening. Therefore, the ripening effect seen with calcium carbide is entirely unrelated to the production of Jasmonic acid.

The incorrect option is 2: Gibberellins

Gibberellins represent a class of plant hormones most commonly associated with promoting stem elongation, seed germination, and flowering. They are critical promoters of overall growth and development in plants. In the context of fruit, their main commercial application often involves increasing fruit size, such as in seedless grapes, or, significantly, *delaying* the onset of senescence and ripening. For instance, Gibberellins are often sprayed on citrus fruits to keep the peel green and firm for longer storage. Since the use of calcium carbide is intended to *accelerate* the ripening process, Gibberellins, which are frequently used to achieve the opposite effect, cannot be the active chemical product.

The incorrect option is 3: Ethylene

Ethylene (C2H4) is, in fact, the essential, naturally occurring plant hormone that governs the ripening of climacteric fruits. It is the gold standard that any artificial method attempts to mimic, and it is the hormone responsible for the final consumer-ready qualities of the fruit. However, the question specifically asks what Calcium carbide *produces*, and the answer to that chemical reaction is Acetylene (C2H2). The use of the cheaper and more readily available calcium carbide is a mechanism that relies on the "false signal" of Acetylene to activate the natural Ethylene-response pathway in the fruit. This practice is dangerous because commercial-grade calcium carbide is often contaminated with toxic impurities, such as arsenic and phosphorus compounds, which pose a severe health risk when transferred to the edible fruit.