Which one of the following was used as a chemical weapon in the First World War?
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Carbon monoxide
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Hydrogen cyanide
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Mustard gas
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Water gas
C
Correct answer
Explanation
Mustard gas (sulfur mustard) was extensively used as a chemical weapon during World War I, causing severe blistering of the skin, eyes, and respiratory tract. It was called mustard gas due to its mustard-like odor and yellow-brown color. While hydrogen cyanide was also used, mustard gas was one of the most widely deployed chemical agents. Carbon monoxide and water gas were not used as chemical weapons.