(13分)某种含有少量FeCl2杂质的FeCl3样品,现要测定其中铁元素的含量。

题型:实验题

问题:

(13分)某种含有少量FeCl2杂质的FeCl3样品,现要测定其中铁元素的含量。实验采用以下步骤进行:

①准确称量m g样品(2~3g);

②向样品中加入10mL 5mol/L的盐酸,再加入蒸馏水,配制成250mL溶液;

③量取25mL操作②中配得的溶液,加入3mL溴水,加热使之完全反应;

④趁热迅速加入浓度为10%的氨水至过量,充分搅拌,使之完全沉淀;

⑤过滤,将沉淀洗涤、灼烧、冷却称量,反复操作至恒重。

请根据上面的叙述回答:

(1)若称量前,托盘天平的指针偏向标尺左方;称量读数时,指针刚好在标尺的中间,则所得样品的质量           

A、比mg多       B、比mg少        C、恰好为mg

(2)溶解样品时要加入盐酸,原因是                           

(3)配制250mL溶液时,除需250mL的容量瓶、烧杯外,还需用到的玻璃仪器是                   

(4)加入溴水时发生反应的离子方程式是                    

(5)若坩埚质量为W1 g,坩埚与灼烧后固体的总质量是W2 g,则样品中铁元素的质量分数是                    

(6)若在配制250mL溶液时,所用的容量瓶没有洗干净。当含有下列物质时,最终会使铁元素的测定含量(填“偏高”、“偏低”或“不变”)。

①NaCl          ②Fe2(SO4)3            ③Mg(NO3)2            

考点:氧化铁单质铁碱式碳酸铜氧化铜
题型:实验题

作为禁止离婚的救济手段的别居制度主要渊源于()

A.欧洲中世纪寺院法

B.日耳曼习惯法

C.罗马法

D.伊斯兰法

题型:实验题

一国在一定时期出口额大于进口额则形成( )。

A.净出口

B.净进口

C.贸易顺差

D.贸易逆差

题型:实验题

About 90 percent of Chinese believe the polarization(分化) between the rich and poor is “serious” in China, according to a survey conducted by China Youth Daily. And more than 80 percent of the respondents(对象) surveyed said something must be done to narrow the expanding gap between the rich and poor, while 14.1 percent said it was necessary.

The polarization has aroused wide concern among the public in recent years. The State Development and Reform Commission(国家发改委) said the Gini Coefficient had reached 0.47 for China, up from o.29 two decades ago. Usually, a country with a number above 0.4 is warned to pay attention to the income inequality problem.

To find out the people’s view, the survey covered 10,250 respondents, between the ages of 20 and 30 with a college education and a monthly salary between 1,000 and 3,000 yuan. Surprisingly, most disagreed with the view of experts who claim the urban-rural difference is causing the widening gap. More than 70 percent of the respondents believed that “ the group of special interests” is the prime reason for the polarization, followed by “people in power” 68 percent, and “bosses” 50 percent.

Another unexpected finding is that almost all agreed that a good educational background and knowledge were not the decisive factors in gaining wealth. About 95 percent said rich people are not necessarily those who are able to speak English or have a college education.

Today in China, rich people , accounting for 10 percent of the population, control 45 percent of the total social fortune, and poor people, also 10 percent of the population, only control 1.5 percent, according to an investigation published by the National Bureau of Statistics last June.

小题1: It can be inferred that the Gini Coefficient ( in paragraph 2) would probably be _____.

A.the unit used in advanced mathematics

B.the degree of a country’s development

C.the level of the citizen’s living standard

D.a measure of income inequality小题2: Experts hold the view that the main reason for the polarization is _____.

A.the urban-rural difference

B.the group of special interests

C.the people in power

D.the bosses小题3:Which of the following can show the correct proportion(比例) of the social fortune among population?

小题4:What’s the best title of the passage?

A.Close the Gap between the Rich and Poor

B.Surveys conducted by China Youth Daily

C.Higher education, Higher pay

D.Rich-Poor Divide Serious, Study Finds

题型:实验题

       “让统治阶级在 * * 主义革命面前发抖吧。无产者在这个革命中失去的只是锁链,他们获得的将是整个世界。”此材料出自于哪一部著作 [ ]

A.《 * * 宣言》

B.《拿破仑法典》

C.《 * * 党宣言》

D.《解放黑人奴隶宣言》

题型:实验题

基站内走线架上走线,交直流电源线与信号线、馈线分别靠走线架两边(),同性质线缆可以(),但必须布放整齐、绑扎固定。严禁()与信号线交叉叠放。

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