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一、选择题 (每小题 2分 ,共 2 0分 ,每题只有一个正确答案 )1.下列变化中 ,属于化学变化的是 ( ) .(A)潮湿空气中铁生锈(B)自行车车胎遇热爆炸(C)以空气为原料制氧气(D)电灯通电发光放热2 .下列物质属于纯净物的是 ( ) .(A)除去灰尘的空气(B)含有少量冰块的水(C)可以?
First, the multiple-choice questions (2 points for each question, a total of 20 points, each question has only one correct answer) 1. The following changes, which are chemical changes (). (A) iron rusty in wet air (B) bicycle tires In case of heat explosion (C) Oxygen is produced by using air as raw material. (D) Electric lamp is energized. Glowing and exothermic 2. The following substances are pure substances: () (A) Dust-removing air (B) Water containing a small amount of ice (C )can?