One question per day; those who answer correctly receive 5 wealth points, and those who participate receive 2 wealth points； Question 297
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Selection: Among the following compounds, which one is commonly used as a fire extinguishing agent? A、Chloroform B、Carbon tetrachloride C、Methyl chloride D、Dichloromethane B、Carbon tetrachloride
The answer is B. Carbon tetrachloride (CCl4), with the chemical formula CCl4. CAS number: 56-23-5, also known as tetrachloromethane, is a colorless, volatile, and non-flammable liquid. It has a slightly sweet odor of chloroform. It also has a pleasant aromatic scent. Molecular weight 153.84, density (20°C) 1.595 g/cm³, melting point –22.8°C, boiling point 76–77°C. At room temperature and pressure, carbon tetrachloride is a colorless, clear, and fluid liquid; in industrial settings it may appear slightly yellow due to the presence of impurities. The vapor of carbon tetrachloride is about 5 times heavier than air and does not burn. The vapor of carbon tetrachloride is toxic; its toxicity is lower than that of chloroform, but it is still quite toxic. Inhaling 2 to 4 milliliters can be fatal to a human. Carbon tetrachloride has very low solubility in water, and it gradually decomposes to form acid salts when exposed to moisture and light. It is soluble in various organic solvents and can mix freely with alcohols, ethers, chloroform, benzene, and petroleum ether. It is an extremely excellent solvent for fats, oils, and various organic compounds.
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