问题 选择题

某溶液中同时含有六种离子:①HS-、②SO32-、③NO3-、④PO43-、⑤SO42-、⑥Na+,向其中加入足量的H2O2,充分反应后溶液中离子浓度基本保持不变的是(  )

A.①②④⑤

B.②③④

C.③④⑥

D.③④

答案

某溶液中同时含有六种离子:①HS-、②SO32-、③NO3-、④PO43-、⑤SO42-、⑥Na+,向其中加入足量的H2O2

①具有还原性,与H2O2发生氧化还原反应,离子的浓度减小;

②具有还原性,与H2O2发生氧化还原反应,离子的浓度减小;

③具有氧化性,不发生反应,离子浓度基本不变;

④具有氧化性,不发生反应,离子浓度基本不变;

⑤不与H2O2发生反应,但②与H2O2发生反应生成SO42-,其离子浓度比原来的大;

⑥不发生任何反应,离子浓度基本不变;

故选C.

阅读理解

阅读理解。

     You may ride on your bicycle in a rush to get to school every morning. You may fight to get a bit of space

on a bus or on the subway.   1         

     No matter where you are, all big cities around the world have traffic jams these days. But although they all

have their problems, many cities also have a type of transport (交通) that has become a cultural icon (圣像).

     In London, to avoid the traffic above ground, people use the "underground",also called the"tube".   2   With

12 lines and 275 stations across the city, the tube, is normally the quickest and easiest way of getting around

London. In London, you are never far from a tube station.

       3   They serve as a quick and easy way of getting across Manhattan, where the subway doesn't take you

everywhere. Stopping a cab is easy; just stick out your arm like you do in any city. But, with over 12,000

yellow cabs in the Big Apple, they also cause traffic jams.

     Since 1873 when the first cable car started public service, the slow and noisy vehicle has been a symbol of

San Francisco. The city was once damaged by a serious earthquake (地震) and challenged (挑战,考验) by cars.   4    

     But there are no such symbols in Los Angeles. If you visit you' d better rent a car.    5   It can take hours

to get across town by bus. The subway covers just a small part of the city center. The light rail line only runs

between the Long Beach hotel area and the city center. That' s why Angelenos love their private cars more than

any other people in the world.

A. However, it is never caught in traffic jams and provides better views than the subway.

B. You may also watch taxis crawl their way through traffic jams.

C. The city has the oldest and most complicated (复杂的 ) underground railway system in

    the world and is the pride of many Londoners.

D. The city' s public transportation is terrible.

E. As darkness fell, hundreds of people in the village left their houses.

F. New York is famous for its yellow cabs.

问答题 简答题