下列有关空气的说法错误的是_刷题宝

题干

下列有关空气的说法错误的是（）

A：按质量计算，空气中含有氮气约78%，氧气约21%

B：空气中各种成分的含量是相对稳定的

C：空气中分离出来的氮气，可以作食品的防腐剂

D：在相同的条件下，用蜡烛代替红磷不可以测量空气中氧气的含量

上一题下一题 0.0难度选择题更新时间:2017-11-28 09:08:58

答案(点此获取答案解析）

A

同类题1

甲、乙、丙、丁四种物质转化关系如右图．已知甲是一种导致钢铁生锈及许多还原性物质变质的单质，化合物乙、丙、丁均含有第三周期一种相同元素R．

同类题2

如图表示细胞膜的亚显微结构，请回答：

同类题3

阅读下面短文，从短文后各题所给四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。

One day, Mary1 shopping with her mother.When they reached 2 the supermarket, Mary was very3.There were many nice things and many people 4 it.

Mary's mother told her 5 her. They walked around and they 6some things for breakfast.

When they came to one shelf(货架).Mary 7 some boxes of chocolate.Mary wanted her mother to buy some8 her.

Her mother gave 9 a box of brown chocolate.Mary shook(摇晃)her head.She wanted a box of white chocolate. Her mother didn't understand her.

“Why do you want a box of white chocolate?” asked her mother.

“I will not bite my fingers(咬手指) when I eat them 10 night.” Answered Mary.

After hearing this, Mary's mother laughed and they left the supermarket happily.

同类题4

下列有关遗传学的说法，正确的是（　　）

同类题5

9. You should give clear ________ for every practice exercise.

小学学科试题库

初中学科试题库

高中学科试题库