题干

实验室里,区分下列各组物质的两个实验设计方案都合理的是(   )

序号

A

B

C

D

需区分的物质

生铁片和纯铁片

氯化钾和硫酸铵

氧化铁粉末和铜粉

氢氧化钙溶液和氯化钙溶液

第一方案

取样,分别加入足量的稀盐酸,观察是否有气泡产生

取样于研钵中,分别加入熟石灰,研磨,闻气味

分别取样,加入试管中,加入氢氧化钠溶液,观察现象

分别取样,加入试管中,测溶液的pH,比较数值

第二方案

取样,互相刻划,观察现象

取样,加入试管中,分别加入稀盐酸,观察现象

分别取样,放在白纸上,观察现象

分别取样,加入试管中,分别通入二氧化碳气体,观察现象

A:A  

B:B  

C:C  

D:D

上一题 下一题 0.0难度 选择题 更新时间:2019-08-05 07:43:26

答案(点此获取答案解析)

D

同类题3

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    The jobs of the future have not yet been invented. ____. By helping them develop classic skills that will serve them well no matter what the future holds.

1). Curiosity

    Your children need to be deeply curious. ____. Ask kids, “What ingredients (配料) can we add to make these pancakes even better next time ?” and then try them out. Ingredients make the pancakes better? What could we try next time?

2). Creativity

    True creativity is the ability to take something existing and create something new from it. ____. There are a dozen different things you can do with them. Experimenting with materials to create something new can go a long way in helping them develop their creativity.

3). Personal skills

    Understanding how others feel can be a challenge for kids. We know what's going on inside our own head, but what about others? Being able to read people helps kid from misreading a situation and jumping to false conclusions. ____. “Why do you think she's crying?” “Can you tell how that man is feeling by looking at his face?” “If someone were to do that to you, how would you feel?”

4). Self expression

    ____ there are many ways to express thoughts and ideas—music, acting, drawing, building, photography. You may find that your child is attracted by one more than another.

A. Encourage kids to cook with you.

B. And we can't forget science education.

C. We can give kids chances to think about materials in new ways.

D. So how can we help our kids prepare for jobs that don't yet exist?

E. Gardening is another great activity for helping kids develop this skill.

F. We can do this in real life or ask questions about characters in stories.

G. Being able to communicate ideas in a meaningful way is a valuable skill.