小亮在实验室发现一瓶盛有无色溶液的试剂瓶,其标签破损,从残余部分只能看出溶质质量

题型:实验题

问题:

小亮在实验室发现一瓶盛有无色溶液的试剂瓶,其标签破损,从残余部分只能看出溶质质量分数为10%,具体是什么物质无法辨认.老师告诉他,这瓶溶液可能是氢氧化钠、氯化钠、氢氧化钙或是碳酸钠中的一种.

(1)小亮查阅氢氧化钙常温下的溶解度为0.18g后,认为该溶液不可能是氢氧化钙,理由是

                                           

(2)小亮取少量样品于试管中,滴加               试液,试液变红色,该溶液不可能是

        (填写化学式),理由是                                

(3)为了确定该溶液的成分,小亮同学继续进行下列实验,请一起参与,并填写下列实验报告.

[设计实验方案]方案甲:选择氯化钙溶液来确定该溶液的成份;方案乙:选择稀盐酸来确定该溶液的成份.

[进行实验]你愿意选择方案       (选填“甲”或“乙”)进行实验.

实验步骤实验现象实验结论
取少量溶液于试管中,

              

                     

              

该溶液是碳酸钠溶液,

有关反应得化学方程式为:

                                      

[实验反思](4)有同学认为还可以用一种常见的碱溶液来确定,那么它是         溶液.

(5)小亮经过反思,向同学们提出如下建议,你认为合理的是      (填序号).

A.倾倒液体时应注意保护标签不被腐蚀   B.要有严谨的科学实验的态度   C.无法辨认的药品,直接倒掉,无需保留.

考点:实验室制取和收集气体的思路二氧化碳的性质实验化学实验数据的分析家庭小实验、趣味实验
题型:实验题

根据所给的首字母填写单词

“Do you like my dress?” She asked a passing stranger. “My mommy made it just for me.” She said with tears in her eyes.

“I think it is really pretty, but why are you (1) c______”

With a quiver (颤抖) in her voice, the little girl answered, “After mommy made me the (2) d______, she had to go to the heaven (天堂).”

Finally the woman realized what the child meant. She gently (3) h____ the child in her arms and together they cried for the mommy that was gone.

Then suddenly the little boy stopped crying, stepped back from the woman and (4) b____ to sing. She sang so softly that it was almost a whisper. It was the sweetest sound the woman had ever heard, a most like the song of a very small bird.

(5) A_____ the child stopped singing, she explained to the lady, “My mommy used to sing that song to me before she went away, and she made me promise to sing it whenever I started crying and (6) i____ would make me stop.”

“See,” she said, “it did, and now my eyes are dry!”

As the woman turned to go, the little girl grabbed her sleeve(袖子). “Madam, can you stay just a minute? I want to show you (7) s________.”

“Of course,” she answered.

(8) P______ to a spot on her dress, she said, “Right here is where my mommy kissed my dress and here,” pointing to another spot, “and here is another kiss, and here, and here.” Mommy said she put all those kisses on my dress so that I would have all kisses for everything that made me cry.

Then the lady (9) r______ that she wasn’t just looking at a dress, no, she was looking at a mother…who knew she was going away and would not be there to kiss away the hurts that she knew her daughter would get. So she took all the love she had for her beautiful little girl and put them into this dress that her child now so proudly wore.

She (10) n____ longer saw a little girl in a simple dress. She saw a child wrapped…in her mother’s love.

题型:实验题

正确处理索赔、防止索赔是建设工程目标控制的( )措施。

A.组织
B.经济
C.技术
D.合同

题型:实验题

在空气中乙炔的含量达到2.8-93%的范围量,遇明火就会产生爆炸。()

题型:实验题

()。

题型:实验题

《水利水电工程施工合同条件》规定,承包人递交了()后,已无权提出任何进一步的索赔要求。

A.最终付款申请

B.完工付款申请

C.工程移交申请

D.发出索赔通知后

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