化学反应前后，一定发生变化的是_刷题宝

题干

化学反应前后，一定发生变化的是（）

A：原子种类

B：分子种类

C：元素种类

D：物质颜色

上一题下一题 0.0难度选择题更新时间:2019-05-29 08:08:15

答案(点此获取答案解析）

B

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f (x) = {(\frac{1}{2})}^{x} - 1 - \log_{2} x

，若x₀是方程f（x）=0的根，则x₀∈（）

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下列语句描述中，描述气候的是（　　）

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