One Question per Day on Synthetic Ammonia (Series 49)

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I. Multiple-choice questions (each question has 4 options, of which only 1 is correct; fill in the correct option in the brackets). Continuing from Series 48: 86. The basic and effective measure to prevent electric shock accidents caused by human contact with charged metal enclosures is ( ). A. Use of safe voltage levels. B. Protective grounding and protective bonding. C. Wearing appropriate protective equipment. D. Use of safe current levels. 87. In chemical manufacturing, what should be used to extinguish initial fires involving flammable gases, flammable liquids, and electrical equipment? A. Acid-base fire extinguishers B. Dry powder fire extinguishers and foam fire extinguishers C. “1211” fire extinguishers D. “1301” fire extinguishers 88. The active component of semi-water gas is ( ). A. CO and CO2 B. H2 and N2 C. CO and H2 D. H2 and O2 89. Before a long-term shutdown of the desulfurization system, it is necessary to first displace the air with an inert gas and then replace that inert gas with air; the oxygen content should be less than ( ) to be considered acceptable. A、10% B、0.5% C、1.0% D、20% 90. When a low-temperature copper oxide catalyst is reduced, its reducing agent is ( ) A、CO and H2 B、H2 and O2 C、H2 and N2 D、CO and CO2 Answer: BBCDA Scoring criteria: 3 points for participation, 1 point for each correct answer, and 1 additional point if the answer is kept hidden. It should be specifically noted that, in order to help everyone remember the practice of hiding answers, starting with this daily question, requests will occasionally be made for respondents to hide their answers. If the answerer is not hidden, they must participate in scoring. For methods to hide posts, see: http://bbs.hcbbs.com/thread-1551107-1-1.html