问题 选择题

下列叙述正确的是(   )

A.95℃纯水的pH<7,说明加热可导致水呈酸性

B.pH = 3的醋酸溶液,稀释至10倍后pH = 4

C.0.2 mol·L-1的盐酸,与等体积水混合后pH = 1

D.pH=3的盐酸溶液,与pH=9的氢氧化钠溶液等体积混合后pH = 7

答案

答案:C

题目分析:A项95℃纯水的pH<7,但水仍呈中性,B项pH=3的醋酸溶液,稀释至10倍后由于存在电离平衡,稀释后的pH<4,D项pH=3的盐酸溶液c(H+)=10-3,pH=9的氢氧化钠溶液c(OH-)=10-5等体积混合后溶液呈酸性。答案选C。

点评:弱电解质在进行稀释过程中存在电离平衡,所以稀释后的pH的变化小于强酸的。

阅读理解

There was one shop in the town of Mufulira which was widely known for its racial discrimination. It was a drugstore. While Europeans were served at the counter, a long line of Africans queued at the window and often not only were kept waiting but were treated rudely by the shop assistants. One day I was determined to make a public protest (抗议) against this kind of thing, and many of the schoolboys in my class followed me to the store,

I simply went into the shop and asked the manager politely for some medicine. As soon as he saw me standing in the place where only European customers were allowed to stand he shouted at me in a bastard (怪声怪气的) language which is only used by a boss when speaking to his servants. I stood at the counter and politely requested in proper English that I should be served. The manager became angry and said, “Even if you stand there till Christmas, I will never serve you.”

I went to the District Commissioner’s office. Fortunately, he was out, for he was one of the old school; however, I saw a young District officer who was a friend of mine. He was very concerned to hear my story and told me that all I had to do was come to him personally and he wou1d buy my medicine for me. I protested that that was not good enough. I asked him to accompany me back to the store and to make a protest to the manager. This he did, and I well remember him saying to the manager,“Here is Mr. Kaunda who is a responsible member of the Urban Advisory Council, and you treat him like a common servant.” The manager of the drugstore apologized and said, “If only he had introduced himself and explained who he was, then, of course I should have given him proper service.”

I had to explain once again that he had missed my point. Why should I have to introduce myself every time I went into a store … any more than I should have to buy my medicine by going to a European friend? I want to prove that any man of any color, whatever his position, should have the right to go into any shop and buy what he wanted, After all, the money which I paid across the counter was exactly the same money as was paid by a European customer.

72. The writer was, at the time of the story, _________.

A. a European officer

B. an African servant

C. a drugstore assistant

D. a black school teacher

73. The manager of the drugstore shouted at the writer in dirty words because     .

A. he could not speak English in a polite way

B. he thought the writer wouldn’t understand English

C. that was the language he used when speaking to Africans

D. that was the only language he could speak when he was angry

74. In paragraph 3, the underlined sentence “he was one of the old school” means    .

A. he stuck to those old racial ideas

B. he graduated from an old white school

C. he was in charge of an old black school

D. he was an old official in the government

75. Why didn’t the writer wait at the window of the drugstore like other Africans?

A. He believed his white friends would help him out.

B. He wanted to fight for equal rights of all black people.

C. He thought he was educated and should he treated differently.

D. He thought, being an important person. he should not be kept waiting.

单项选择题