问题 选择题

某温度下,0.1mol•L-1NaHCO3溶液pH=10,下列判断正确的是(  )

A.溶液中碳酸氢根电离的氢离子浓度为10-10mol•L-1

B.c(Na+)>c(OH-)>c(HCO3-)>c(H+

C.溶液中水电离的氢氧根离子浓度为10-4mol•L-1

D.c(Na+)+c(H+)=c(HCO3-)+c(OH-

答案

A、0.1mol•L-1NaHCO3溶液pH=10,碳酸氢根离子水解大于电离,溶液呈碱性,氢离子浓度为10-9mol/L,是水电离剩余在溶液中氢离子浓度,不是碳酸氢根电离出的氢离子,故A错误;

B、0.1mol•L-1NaHCO3溶液pH=10,碳酸氢根离子水解大于电离,溶液呈碱性,溶液中离子浓度大小为c(Na+)>c(HCO3-)>c(OH-)>c(H+),故B错误;

C、常温下,依据溶液中离子积常数计算溶液中水电离的氢氧根离子浓度为10-4mol•L-1,故C正确;

D、0.1mol•L-1NaHCO3溶液pH=10,溶液中存在电荷守恒c(Na+)+c(H+)=c(HCO3-)+c(OH-)+2c(CO32-),故D错误;

故选C.

单项选择题
阅读理解

阅读理解。

     Joanne was stuck in a traffic jam in central Birmingham at 5:30, and at 6:30 she was expected to be

chairing a meeting of the tennis club. At last, the traffic was moving. She swung quickly racing to her house.

As she opened the door, she nearly tripped over Sheba.

     "Hey, Sheba," she said, "I've got no time for you now, but I'll take you out as soon as I get back from

tennis club." Then she noticed Sheba seemed to be coughing or choking. Obviously, she could hardly breathe.

Immediately, Joanne realized she would have to take her to the vet (兽医). When she got there, the vet was

just about to close for the day. Seeing the state of Sheba, Dr. Sterne brought her quickly into his office.

     "Listen, doctor, I'm really in a rush to get to a meeting-can I leave her with you, and go and get changed?

I'll be back in ten minutes to pick her up, and then I'll take her on to the meeting with me. Is that OK?"

     "Sure," said the doctor.

     Joanne made the quick trip back to her house in a couple of minutes. As she was once more entering the

hallway, the phone by the door began to ring.

     "This is Dr. Sterne," said an anxious voice. "I want you to get out of.that house immediately," said the

doctor's voice. "I'm coming round right away, and the police will be there any time now. Wait outside!"

     At that moment, a police car screeched to a stop outside the house. Two policemen got out and ran into

the house. Joanne was by now completely confused and very frightened. Then the doctor arrived.

     "Where's Sheba? Is she OK?" shouted Joanne.

     "She's fine, Joanne. I took out the thing which was choking her, and she's OK now."

     Just then, the two policemen reappeared ffom the house, half-carrying a white-faced man, who could

hardly walk. There was blood all over him.

     "My God," said Joanne, "how did he get in there? And how did you know he was there?"

     "I think he must be a burglar," said the doctor. "I knew he was there because when I finally removed what

was stuck in Sheba's throat; it turned out to be three human fingers."

1. What was Joanne supposed to do at 6:30? [ ]

A To walk her dog.

B. To see her doctor.

C. To attend a club meeting.

D. To play tennis with her friends.

2. Joanne wanted to get back to her home again _____. [ ]

A. to dress up for the meeting

B. to phone the police station

C. to catch the badly hurt burglar

D. to wait for her dog to be cured

3. From the passage, we can infer that _____.[ ]

A. Sheba fought against the burglar

B. the police found the burglar had broken in

C. Joanne had planned to take her dog to the meeting

D. the doctor performed a difficult operation on the dog

4. In this passage, the writer intends to tell us that the dog is _____. [ ]

A. clever

B. friendly

C. frightening

D. devoted