Penicillin, Biogas, Citric acid, Curd.
Penicillin is the most important because it is an important antibiotic used to treat a variety of bacterial infections and has saved countless lives since its discovery. Biogas is the second most important as it is a renewable source of energy that can be used for cooking, heating, and electricity generation, which can help reduce our dependence on non-renewable fossil fuels. Citric acid is important in the food and beverage industry as a flavor enhancer and preservative. Curd is the least important as it mainly serves as a source of nutrition and does not have as significant an impact on human society as the other three.
Penicillin is the most important because it is an important antibiotic used to treat a variety of bacterial infections and has saved countless lives since its discovery. Biogas is the second most important as it is a renewable source of energy that can be used for cooking, heating, and electricity generation, which can help reduce our dependence on non-renewable fossil fuels. Citric acid is important in the food and beverage industry as a flavor enhancer and preservative. Curd is the least important as it mainly serves as a source of nutrition and does not have as significant an impact on human society as the other three.