问题 选择题

现有常温下的五种溶液(如下表)。

下列有关叙述中正确的是

A.五种溶液中,水电离出的c(OH)最小的是⑤

B.将①、④两种溶液等体积混合,所得溶液中:c(Cl-)>c(NH4+)>c(OH-)> c(OH-)。

C.分别将①、②、③、④加水稀释100倍,稀释后四种溶液的pH:①>②>③>④

D.在⑤中加入适量的④至溶液呈中性,所得溶液中:c(Na+)>c(CH3COO-)> c(Cl-)>c(OH-)= c(H+)。

答案

答案:D

题目分析:A.五种溶液中,①、②、③、④都是对水的电离起抑制作用,而且抑制的程度相同,但是⑤是强碱弱酸盐,对水的电离起促进作用,所以水电离出的c(OH-)最大的是⑤。错误。B.氨水是弱碱,盐酸是强酸。若将①、④两种溶液等体积混合,由于碱过量,所以所得溶液是NH4Cl与NH3·H2O的混合溶液。由于NH3·H2O的电离作用大于NH4Cl的水解作用。所以c(NH4+)>c(Cl-).电离使溶液显碱性,所以c(OH-)>c(H+).盐的电离大于弱电解质的电离作用,因此c(Cl-)>c(OH-)。所以溶液中的两种浓度关系为c(NH4+)>c(Cl-)> c(OH-)>c(H-)。错误。C.①、③是弱电解质,加水稀释时pH变化较小,而②、④是强电解质,加水稀释时pH变化较大。若将这四种溶液加水稀释100倍,稀释后四种溶液的pH:①>②>④>③。错误。D.在⑤中加入适量的④至溶液呈中性,所得溶液是NaCl、CH3COONa、CH3COOH的混合溶液。由于加入的HCl量较小,所以离子浓度关系是c(Na+)>c(CH3COO-)> c(Cl-)>c(OH-)= c(H+)。正确。

选择题
阅读理解

More American people take their troubles with them on holiday, according to a new survey. Although 40 percent said that the main reason for going away is to escape pressure (压力) from work, almost all said they worry more than they do at home. Only four in every 100 said that they are happy and free of care.

The most common worry is burglary ( 入室盗窃), with four out of 10 worrying about their homes being broken into while they’re abroad. More than a quarter fear they will feel crazy with some other noisy and rough holiday-makers and 22 percent worry they may be attacked or their possessions will be missing. One in five think the car may break down; and the same number worry about the chances of bad weather.

The survey also showed that the stay-at-home Americans are no more. Three out of every five want to have a holiday abroad, a great increase from the figures only three years ago. The hotel holiday is still a winner, with about one third of all Americana preferring to go on a self-catering ( 自助 ) holiday.

56. The underlined word “survey” in the first paragraph most probably means ______.

A. research               B. review            C. exhibition        D. examination

57. According to the text, about ______ of people worry more on holiday than when they are at home.

A. 25%             B. 40%               C. 80%             D. 95%

58. The third most common worry of American holiday-makers is that they may ______.

A. be attacked or lose their possessions  B. have problems with their cars on the road

C. have bad weather on holiday      D. get mixed with some rough fellow holiday-makers

59. Where do American holiday-makers like to stay most?

A. At a hotel.                 B. In a quiet place.         

C. At a friend's house.           D. Where they can cook for themselves.