题干

 某校课外小组同学用含有泥沙和氯化钠杂质的碳酸钠样品进行了如下实验:向一只60 g的烧杯中加入35 g样品,然后分5次加入盐酸,每次加入盐酸40 g(不考虑水、氯化氢逸出),每次反应完全后,称量烧杯和烧杯内物质的总质量。记录实验数据如下:   

加入稀盐酸次数1234    5
烧杯和烧杯内物质的总质量/g132.8170.6208.4246.2286.2

已知:(1)第5次加酸后,烧杯底部剩余不溶固体2.1g。泥沙成分为SiO2,它不溶于水,也不与盐酸发生反应。
(2)Na2CO3 + 2HCl= 2NaCl + H2O + CO2
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同类题2

阅读材料,完成下列要求。

材料一  中国古代慈善的概念实际上等同于社会保障。孔子认为只有调均才能维护社会稳定,这一思想被汉代的董仲舒作了更为直白的阐述,认为要使社会易治就必须“使富者足以示贵而不致于骄,贫者足以养生而不致于忧”。董仲舒还认为天和人是相通的,使得历代统治者把天灾看成是上天对自己的警示。在统治者看来,灾害的发生在极大的程度上来源于自身,因此自己有责任解除臣民的生存危机。

古代社会保障机构主要有官办、民办、宗教开办、宗族内部救助、商人互助等种类。在频繁的自然灾害风险中,我国更加重视灾后的救助。对于弱势群体,官府以及其他社会保障机构总是将对他们的保障当作自己的责任,形成了一套行之有效的保障制度与措施,其内容主要基于国家减灾和储备的防御性保障、老年保障、临灾生活保障、弱势群体或不幸人群保障。为了使有关社会保障的诏令或制度落实到实处,中央政权往往建立对各级官员的考核监督体制,并对保障实施中可能出现的漏洞予以防范。

——摘蝙自王君南《基于救助的社会保障体系——中国古代社会保障体系研究论纲》

材料二  1834年英国颁布了新济贫法,它的主题和基调是通过惩治“懒惰”贫民根治贫穷问题。19世纪70年代后,许多人开始将贫困问题视为影响国家发展、社会进步的障碍。在贫困问题上,国家开始采取更为积极的措施。1861年到1891年,英国每年增加的1000张病床中,有3/4是在济贫院医院。政府还建设一批条件较好的济贫院,采取一定措施改善济贫院的物质与精神娱乐。1891年后,开始为老年贫民购买书籍报纸,为儿童购买玩具。从1875-1888年14年间总共完成了16项贫民窟的改造工作。在贫民的教育方面,政府也加大干预力度,英国政府于1 880年开始推行《强制教育法》,将初等教育视为民众必须遵守的国家义务。1891年,初级教育做到了完全免费。

——摘鳊自郭家宏《19世纪末期英国贫困观念的变化》

同类题5

阅读理解

B

    When people ask Kazumi.“What do you do?”,she answers.“I'm a dentist.”Then she watches for the look on their faces.She can see that they are thinking.“I don't like dentists.”She understands how they feel.They are afraid of the drills and pain(钻头和疼痛).

    Kazumi does not want her patients (病人) to feel scared.She takes time to talk to them and make them less afraid.She tells them.“I'm going to be as gentle (温柔的)as I can.I don't like pain myself !”

    When she was a child.Kazumi did not like going to the dentist.She never expected to become one herself.She used to think about becoming a reporter when she grew up.She was interested in talking with different people.Now Kazumi has a different job,but communication is still a big part of her job.She needs to talk with her patients.They need to understand each other.

    Kazumi feels great about her job.She gives three reasons why she is glad to be a dentist.First of all,she knows that she makes her mother happy.Her mother is glad that Kazumi can support herself.She told her daughter, “You won't have to depend on others.It's good for you!”Kazumi also likes working with her hands.A dentist needs great control of very small movements.“I think I have good hands for this kind of work,”she says.Finally, she likes learning new things.As a dentist, she learns from experience and from talking with her boss(老板).Every Friday afternoon, she talks with her boss about her problems at work,and he gives her advice.She has learned a lot from him.