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一、选择题 1.属于纯净物的是①水煤气②粗食盐③纯盐酸④冰和水 2.下列变化不表现出物质化学性质变化的是①从液态空气中分离出氧气②高温下煅烧石灰石③钠原子变成钠离子④米制酒 3.将下列物质加水振荡后,溶液pH值小于7,滴入紫色石蕊试液显红色的是①SiO_2②NaCl③CaO④SO_3 4.元素的化学性质主要决定于原子的是①核外电子层数②最外层也子数③核外电子总数④核电荷数 5.下列物质中硫元素的化合价为-2价的是①H_2S②SO_2③Na_2SO_3④H_2SO_4
First, the multiple-choice questions 1. Belong to the pure material ① water gas ② crude salt ③ pure hydrochloric acid ④ ice and water 2. The following changes do not show the change of chemical properties is ① oxygen from liquid air ② calcined limestone at high temperature ③ Sodium atoms into sodium ions ④ rice wine 3. The following substances water shake, the solution pH value is less than 7, the drop was purple litmus test was red ①SiO2_2NaCl③CaO④SO_3 4. The chemical nature of the element is mainly determined by the atomic ① nuclear Outer electron layers ② outermost sub-population ③ total number of extranuclear electrons ④ nuclear charge number 5. The valency of sulfur element in the following substances is -2: ①H_2S②SO_2③Na_2SO_3④H_2SO_4