下列说法不正确的是
A．气态I2与固态I2都能使淀粉变蓝色，说明同种分子化学性质相同
B．水在通电条件下生成氢气和氧气，说明分子在化学变化中发生了变化
C．加热的铁丝在空气与在纯氧中现象不同，是因为氧气的纯度不同
D．大自然有自净作用，所以人类不用担心环境污染
答案：D
分析：应用构成物质的微粒具有如下特征：①体积和质量都很小，②微粒之间存在间隔，③微粒是在不断运动的，④化学变化的本质是分子分解成原子，原子重新组合成新的分子的过程．解释作答．
解答：解：
A、固体碘、碘蒸气，均能使淀粉溶液变蓝色说明相同物质的分子，其化学性质相同； 正确；
B、水在通电的情况下生成氢气和氧气，说明在化学变化中分子能够再分； 正确
C、加热铁丝在空气中和在氧气中的现象不同，是因为氧分子的浓度不同； 正确；
D、空气人为的被污染已超过大自然的自净作用，需保护环境，热爱大自然； 不正确．
故选D
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