问题 选择题

电解质溶液有许多奇妙之处,你只有深入思考,才能体会到它的乐趣。下列关于电解质溶液的叙述中正确的是

A.Na2CO3、NaHCO3两种盐溶液中,离子种类不相同

B.常温下,1mol/L的CH3COOH溶液与1mol/L的NaOH溶液等体积混合,所得混合液中:c(Na+) >c(CH3COO-) >c(H+)>c(OH-)

C.物质的量浓度相同的NH4Cl和NH4HSO4两种溶液中,c(NH4+)前者小于后者

D.常温下,某溶液中有水电离出的c(H+)=10-51mol·L-1,则此溶液可能是盐酸

答案

答案:C

题目分析:A、的Na2CO3、NaHCO3两种盐溶液,阴离子都是 CO32-,HCO3-,OH-,故A错误;B、1 mol•L-1的CH3COOH溶液与1 mol•L-1的NaOH溶液混合,等体积混合,溶液呈碱性,故B错误;C、NH4HSO4溶液中,H+抑制NH4+水解,故C正确;D、常温下,水的离子积为10-14,水电离出的c(H+)=c(OH-)=10-7,酸或碱的溶液抑制水的电离,该溶液中c(H+)=10-5mol•L-1,水的电离程度程度,则此溶液不可能是盐酸,可能是强酸弱碱盐,故D错误.

填空题
阅读理解

According to the United States government, people are classified as homeless if they have no place to stay and no expectation of finding a place for the next thirty days. Although technically accurate, that is an impersonal assessment of an enormous and very human problem.

The homeless population represents all of us Americans. It includes men and women, the elderly, children, and infants. Its members are from all ethnic groups. What they have in common is poverty.

Currently in the U.S., thirty-nine million people live in poverty. When money is really tight, paying the rent or buying food often becomes a choice. Government assistance in the form of food stamps does help but, as one homeless man explains, you can’t pay the rent with food stamps.

With no money for rent, the streets and homeless shelters become the alternative.

Although men make up the largest group within the homeless population, homeless women with children are rapidly joining them. In fact, one quarter of the homeless people in the U.S. are teenagers and young children.

People may become homeless for numerous reasons. However, there are certain factors that many of these individuals have in common. They include a lack of adequate education and job skills. A majority of the teenagers and adults have not completed high school.

The abuse of alcohol and drugs is also a common factor. One third of the adult homeless population abuses alcohol, while one quarter of the same group uses drugs.

Some members of this population suffer mental health problems. Within the past several years many institutions for the mentally ill have been closed and their patients sent “home”. Unfortunately, a number of those people have no home to go to and they are unable to adequately look after themselves.

Job loss in today’s economy has also become a real factor in the loss of people’s homes. The breakup of families through abandonment and divorce is also contributing factors, particularly when there are children involved. The parent who is left to care for the kids with inadequate income may be forced to depend on the homeless shelters to put a roof over their heads.

小题1:The writer thinks that the U.S. government’s definition for the homeless shows _________.

A.an insincere attitude toward the homeless

B.an unbearable attitude toward the homeless

C.an uncivilized attitude toward the homeless

D.an unsympathetic attitude toward the homeless小题2:The U.S. government helps the homeless by _________.

A.giving them homeless allowance

B.giving them food stamps

C.finding jobs for them

D.finding residence (a place to live) for them小题3:People become homeless for all the following reasons EXCEPT _________.

A.the lack of adequate education

B.the abuse of alcohol and drugs

C.the closure of institutions for the mentally ill

D.the poor performance of economy小题4:The breakup of families is likely to lead to homelessness because a parent with kids may _________.

A.lose his or her job in today’s economy

B.be unable to look after the kids

C.not have enough income

D.find residence at a homeless shelter