题干

一定条件下,在固定容积的密闭容器中,能表示反应X(g)+2Y(g)⇌2Z(g)一定达到化学平衡状态的是(  )

①X、Y、Z的物质的量之比为1:2:2 

②容器中气体的密度不再发生变化

③容器中气体的压强不再发生变化     

④单位时间内生成n mol Z,同时生成n mol X.

A:①②

B:①④     

C:②③

D:③④

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D

同类题4

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    When Abraham Lincoln was young, he worked in a store. One day a woman came into the store and bought some things. They added up to two dollars and six and a quarter cents.

    The bill was paid, and the woman was satisfied. But the young storekeeper, not feeling quite sure about his calculations(计算), added up the things again. To his surprise, he found that it should have been but two dollars.

    “I've made her pay six and a quarter cents more,” said young Abe, upset.

    It was an unimportant thing, and many salespersons would forget it, but Abe was too careful for that.

    The money must be paid back, he decided.

    At night, he closed the store and walked to the home of his customer. He explained the matter, paid over the six and a quarter cents, and returned satisfied.

    Here is another story of young Lincoln's strict honesty. A woman entered the store and asked for half a pound of tea. The young man weighed it out. This was the last sale of the day.

    The next morning, when beginning his duties, Abe discovered a four-ounce weight on the scales(磅砰). It flashed upon him at once that he had used this in the sale last night, and so, of course, given his customer short weight. Many people would not have been much worried by this discovery. But Abe weighed out four ounces of the tea, shut up the store, and carried it to the customer. I think that the name, so often given in late times to President Lincoln, of “Honest Old Abe", was well deserved(应得的).

同类题5

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