问题 选择题

下列说法正确的是(   )

A.强电解质都是离子化合物,而弱电解质都是共价化合物

B.中和PH值相等、体积相等的盐酸和醋酸,盐酸所消耗的氢氧化钠少

C.将氢氧化钠和氨水溶液各稀释一倍,两者的OH-浓度均减小到原来的1/2

D.常温下,PH为12的溶液一定是碱溶液

答案

答案:B

强电解质也不一定都是离子化合物,例如氯化氢是共价化合物,A不正确;醋酸是弱酸,所以在pH相等的条件下,醋酸的浓度大于盐酸的,所以盐酸消耗的氢氧化钠少,B正确;氨水是弱电解质,存在电离平衡。稀释促进电离,所以选项C不正确;选项D不正确,只能说该溶液显碱性,但溶液不一定是碱液,所以正确的答案选B。

填空题
阅读理解

阅读理解。

      Researchers have found more evidence that suggests a relationship between races and rates(率)

of lung cancer among smokers. A new study shows that black people and Native Hawaiians are more

likely to develop lung cancer from smoking. It compared their risk to whites, Japanese-Americans and

Latinos.

     Researchers at the University of Southern California and the University of Hawaii did the new study.

The New England Journal of Medicine published the findings. The eight-year research studied more than

180,000 people. They included present and former smokers and people who never smoked. Almost

2.000 people in the study developed lung cancer.

     Researchers say genetics(遗传学) might help explain the racial and ethnic(种族的) differences.

There could be differences in how people's bodies react to smoke. But environmental influences,

including the way people smoke, could also make a difference.

      African-Americans and Latinos in the study are reported smoking the fewest cigarettes per day.

Whites are the heaviest smokers. But the scientists point out that blacks have been reported to breathe

cigarette smoke more deeply than white smokers. This could fill their lungs with more of the chemicals

in tobacco that cause cancer.

      Scientists know that some diseases effect different groups differently. And some drug companies

have begun to develop racially targeted(针对) medicines. Last June, the United States Food and Drug

Administration approved a drug designed to treat heart failure in black patients. The name is BiDil. The

agency called it "a step toward the promise of personalized medicine."

1.Which of the following orders is from higher to lower risk of having lung cancer?

A.Whites-Native Hawaiians

B.Africans-Americans-Latinos

C.Asians-Native Hawaiians

D.Africans-Americans-Native Hawaiians

2.Researchers agree that it is      that may probably determine black people's risk of lung cancer.

A.the larger amount of smoking than white people

B.the living style or habit of the blacks

C.the depth of cigarette smoke into their lungs

D.the physical strength to react to cigarette smoke

3.People in the new study are made up of          .

A.heavy smokers in America

B.the black and white people

C.the Asians and Hawaiians

D.smokers and non-smokers

4.The production of BiDil referred to in the last paragraph is to      .

A.explain different races react to some diseases differently

B.tell the readers that racial differences exist in smokers

C.show a big step people have taken in the medicine area

D.support the idea that it is easy for blacks to have cancers

5.Which of the following statements is TRUE according to the author?

A.The way of smoking may increase the risk of lung cancer.

B.Race has nothing to do with the risk of having a lung cancer.

C.The research was started by the New England Journal of Medicine.

D.The risk of lung cancer lies I how much a person smokes.