铬酸铅俗称铬黄,不溶于水。广泛用于涂料、油墨、漆布、塑料和文教用品等工业。实验室

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问题:

铬酸铅俗称铬黄,不溶于水。广泛用于涂料、油墨、漆布、塑料和文教用品等工业。实验室模拟工业上用铬污泥(含有Cr2O3、Fe2O3、A12O3、SiO2等)制备铬黄的工艺流程如下:

(1)将铬污泥粉碎的目的是                     ,操作a的名称为          

(2)废渣的主要成分是A1(OH)3和Fe(OH)3。已知25℃时,A1(OH)3的Ksp=1.3×1033,则该温度下反应Al3++3H2OAl(OH)3+3H+的平衡常数为          (保留两位有效数字);

(3)写出加入30%H2O2过程中发生的离子反应方程式:                     

(4)实验室洗涤铬黄沉淀的方法:                                           

(5)写出浓盐酸与A12O3反应的离子方程式:                                

考点:光导纤维新型材料(新型陶瓷、单晶硅等)塑料、纤维、橡胶复合材料
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The cost of medical care in the United States is very high. The time and money that doctors spend on their medical education is probably one reason for this problem.

A visit to a doctor’s office costs from 15 to 50 dollars. It’s so expensive. Many people in the United States think that doctors are overpaid. However, most doctors disagree. They say that they were asked to study medicine for a long time. Tuition for many years of medical education costs a lot of money. Doctors say that it is necessary for most medical students to borrow money from the bank to pay their tuition. Because their money must be repaid to the bank, young doctors need to receive a lot of money for their work. So they charge(收费)people high prices for medical care.

Therefore the cost of medical care in America is high. Because high tuition is one cause of high costs, one way to lower costs would be to have medical school that are free or have low tuition.

小题1:The underlined word "tuition" in the passage means “______”

A.eating at school

B.studying the courses

C.money used for education

D.living at school小题2:The main idea of the passage is that______.

A.a visit to a doctor’s office may cost much in the USA

B.the cost of medical care is the only reason for the high costs in the USA

C.medical care in the USA costs a lot of money because doctors want to be rich

D.the high cost of tuition in medical schools is one reason for the high cost of medical care in the USA小题3: The cost of medical care in the USA is very high. What does the writer think about it?

A.He agrees that doctors are overpaid.

B.He thinks it is a big problem and suggests (建议) solving (解决) it.

C.He doesn’t think the medical students should borrow money from banks.

D.He doesn’t think it necessary for the medical students to study for a long time.

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急性黄疸型肝炎,起病几天以内迅速出现重型肝炎表现者,可诊断为急性重型肝炎

A.5天

B.7天

C.10天

D.14天

E.15天

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多聚甲醛

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我装置操作现场噪声控制标准是小于或等于94分贝。

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“各时代的统一性是如此紧密,古今之间的关系是双向的。对现代的曲解必定源于对历史的无知;而对现实一无所知的人,要了解历史也必定是徒劳无功的。”这强调的是()。

A.古为今用

B.以古讽今

C.厚今薄古

D.贯通古今

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