问题 填空题

如图是实验室加热氯酸钾(KClO3)与二氧化锰(MnO2)的混合物制取氧气的装置图.

(1)写出用反应文字表达式(或化学符号表达式):______;

(2)下列操作顺序合理的是______(填序号);

①先加药品、再检查装置的气密性

②先检查装置的气密性、再加药品

(3)实验结束后,若要回收MnO2,则可将试管内的剩余物经溶解、______、洗涤、干燥等加以回收.

答案

(1)实验室用氯酸钾和二氧化锰制取氧气的反应表达式为:氯酸钾

二氧化锰
加热
氯化钾+氧气,化学符号表达式为:KClO3
MnO2
KCl+O2

(2)制氧气的操作步骤是:检查装置的气密性,装药品、固定,收集氧气;故操作顺序合理的是②;

(3)实验结束后,若要回收MnO2,二氧化锰不溶于水,生成物氯化钾溶于水,因此可将试管内剩余物经溶解、过滤、洗涤、干燥等加以回收;

故答案为:(1)氯酸钾

二氧化锰
加热
氯化钾+氧气(或KClO3
MnO2
KCl+O2);

(2)②;

(3)过滤.

阅读理解

Age has its special advantage in America. And one of the more impressive of them is the senior citizen discount. Anyone who has reached a certain age—in some cases as low as 55-is automatically entitled to plenty of price reductions at nearly every level of commercial life. Eligibility(资格)is determined not by one’s need but by the date on one’s birth certificate. Practically the discounts have become a routine part of many businesses-as common as color televisions in motel rooms and free coffee on airliners.

People with gray hair often are given the discounts without even asking for them;yet, millions of Americans above age 60 are healthy and solvent(有支付能力的). Businesses that would never dare offer discounts to college students or anyone under 30 freely offer them to older Americans. The practice is acceptable because of the widespread belief that “elderly” and “needy” are synonymous(同义的). Perhaps that once was true, but today, to be sure, there is economic variety within the elderly, and most of them aren’t poor.

It is impossible to determine the effect of the discounts on individual companies. For many firms, they are a stimulus to income. But in other cases the discounts are given at the expense, directly or indirectly, of younger Americans. Moreover, they directly annoy some politicians and scholars who consider it a coming conflict between the generations.

Generational tensions are being fueled by continuing debate over Social Security benefits, which mostly involves a transfer of resources from the young to the old. Employment is another point. Supported by laws and court decisions, more and more older Americans are refusing the retirement dinner in favor of staying on the job-thereby lessening employment and promotion opportunities for younger workers. Far from a kind of charity they once were, senior citizen discounts have become a powerful economic privilege(特权)to a group with millions of members who don’t need them.

It no longer makes sense to treat the elderly as a single group whose economic needs deserve priority over those of others. Senior citizen discounts only enrich the myth that older people can’t take care of themselves and need special treatment;and they threaten the creation of a new myth, that the elderly ale ungrateful and taking for themselves at the expense of children and other age groups. Senior citizen discounts are the heart of the very thing older Americans are fighting against-discrimination by age.

小题1:We learn from the first paragraph that   .

A.offering senior citizen discounts has become routine commercial practice

B.senior citizen discounts have enabled many old people to live a good life

C.giving senior citizen discounts has increased the market for the elderly

D.senior citizens have to show their birth certificates to get a discount小题2:The reason to give the senior citizen discount is that   .

A.the elderly need humane help from society

B.businesses should do something for society in return

C.old people are entitled to special treatment for their contribution to society

D.the senior discounts can make up for the lack of the Social Security system小题3:What does the author think of the Social Security system?

A.It encourages elderly people to retire in time.

B.It opens up broad career chances for young people.

C.It benefits the old at the expense of the young.

D.It should be strengthened by laws and court decisions.小题4:What does the author mainly argue in the passage?

A.Senior citizens should fight hard against age discrimination.

B.The elderly are selfish and taking senior discounts for granted.

C.Senior citizen discounts may well be a type of age discrimination.

D.Discount should be given to the economic needs of senior citizens.

单项选择题 A3/A4型题