题干

下列叙述错误的是(   )

A:把aL0.1mol.L-1的CH3COOH溶液与bL0.1 mol.L-1的KOH溶液混合,所得溶液中一定存在:c(K+)+c(H+)=c(CH3COO-)+c(OH-)

B:把0.1mol.L-1的NaHCO3溶液与0.3 mol.L-1的Ba(OH)2溶液等体积混合,所得溶液中一定存在.:c(OH-)>c(Ba2+)>c(Na+>c(H+)

C:向1 mol.L-1的CH3COOH溶液中加入少量CH3COONa固体,由于CH3COONa 水解显碱性,所以溶液的pH升高

D:常温下,在pH=3的CH3COOH溶液和pH=11的NaOH溶液中,水的电离程度相同

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C

同类题1

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    In 1975, George Carlin appeared on a popular TV show, Saturday Night Live, with his famous words about blue food. “Why is there no blue food? I can't find blue food—I can't find the flavor of blue! I mean yellow is lemon; orange is orange and red is cherry. Where is the blue food?”

    Well, Carlin pretty much has it right—there is not no blue food, but there's certainly not a lot of it. Fresh-picked blueberries are blue, though they become purple when they are turned into jam. The blue in blueberries—like the purple in grapes and red in tomatoes—is found in nature. But it isn't a hot color for food. People don't seem to prefer blue food. Some diet programs even suggest that those determined to lose weight should make their food blue.

    Eating, in part, begins with our eyes. Chares Spence—an experimental psychologist from Oxford University—points out that color can change our taste experience. Commonly, we consider red-colored foods up to 20% sweeter than they actually are; and green foods as being more sour. Spence suggests: human expectations may be influenced by our long history of watching—green fruits can become sweet as they grow up and turn red.

    But what about blue? Except blueberries, much of the blue food we see these days is dyed blue artificially. Food producers argue that artificial color doesn't do much damage to health. A lot of research shows that some physical problems of kids are related to food dyes—while other studies show no effects at all. Blue birthday cake or even blue-dyed chicken can be served on the dinner table. So what?

同类题4

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    Let children learn to judge their work.____ If corrected too much, he will stop talking. He notices a thousand times a day the difference between the language he uses and the language those around him use. Bit by bit, he makes the necessary changes to make the necessary changes to make his language like other people's.____They learn to do without being taught to walk, run, climb, whistle, ride a bicycle, compare their own performances with those of more skilled people, and slowly make the needed changes.

    But in school we never give a chance to find out his mistakes and correct them by himself.____ We act as if we thought that he would never notice a mistake unless it was pointed out to him, or correct it unless he was made to. Let him work out, with the help of other children if he wants it, what this word says, what the answer is to that problem, whether this is a good way of saying or doing this or not.

    If it is a matter of the right answer, as it may be in mathematics or science, give him the answer book.____Why should we teachers waste time on such routine work?____ Let the children learn what all educated people must some day learn, how to measure their own understanding, and how to know what they know or do not know.

A. Children leant to do all the other things in the same way.

B. Let him correct his own papers.

C. Point out his mistakes.

D. We do it all for him.

E. We allow him to learn from other children.

F. A child learning to talk does not learn by being corrected all the time.

G. Our job should be to help the child when he tells us that he can't find the way to get the right answer.