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例1(2015年北京市中考题)钙是构成人体骨骼和牙齿的重要组分,这里的“钙”是指()。A.钙元素B.钙原子C.钙单质D.钙离子分析:食品、药品、营养品、人体等中的“钙”等不是以单质、分子、原子、离子等形式存在,而是指元素,通常用元素及其所占质量(质量分数)来描述。解:钙是构成人体骨骼和牙齿的重要组分,这里的“钙”不是以单质、分子、原子、离子等形式存在,这里所指的“钙”是强调存在的元
Example 1 (Beijing 2015 senior high school entrance examination questions) Calcium is an important component of the human skeleton and teeth, where “calcium” means (). A. Calcium element B. Calcium atom C. Calcium element D. Calcium ion analysis: The “calcium” in food, medicine, nutrition, human body and the like is not in the form of simple substance, molecule, atom, ion, Refers to the elements, usually with the elements and their share of quality (mass fraction) to describe. Solution: Calcium is an important component of the body’s bones and teeth. Here, “calcium” does not exist in the form of simple substance, molecule, atom, ion, etc. The term “calcium”