Which of the following gases was originally discovered by Scheele?
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Answer: A. chlorine
Explanation
Chlorine gas was first discovered and successfully isolated by the Swedish-German chemist Carl Wilhelm Scheele in 1774. Scheele produced the greenish-yellow gas by reacting hydrochloric acid with the mineral pyrolusite containing manganese dioxide. His pioneering chemical experiments laid the foundation for understanding halogen chemistry and elemental gas properties. Carl Wilhelm Scheele was a prolific eighteenth-century pharmacist and chemist credited with discovering several chemical elements. Chlorine is a highly reactive halogen gas possessing strong bleaching and disinfecting chemical properties in aqueous solutions. Pyrolusite is a naturally occurring mineral composed primarily of manganese dioxide used historically in chemical manufacturing.
Hydrogen gas was first artificially produced and recognized as a distinct substance by Henry Cavendish in 1766. Oxygen was independently discovered by Joseph Priestley and Carl Wilhelm Scheele, but Scheele is specifically credited for chlorine. Carbon dioxide was studied extensively by Jan Baptista van Helmont and Joseph Black long before Scheele isolated chlorine.
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