问题 选择题

某工厂拟选用下列物质处理含硫酸的废水,想花最少的钱中和等量的废水应选择(  )

物  质氯化钠碳酸钙熟石灰氢氧化钠
市场参考价(元/kg)1.21.82.011.5

A.氯化钠

B.碳酸钙

C.熟石灰

D.氢氧化钠

答案

A、根据氯化钠和硫酸不会反应,不能中和废水,故A错误;

B、硫酸会与碳酸钙反应生成微溶于水的硫酸钙,阻碍反应的继续进行,故B错误;

C、氢氧化钙会与硫酸发生中和反应,价格适中,故C正确;

D、虽然氢氧化钠会中和硫酸分子,但是氢氧化钠的价格贵,中和一个分子硫酸需要两个氢氧化钠分子,故D错误;

故选C.

填空题
单项选择题

Manners nowadays in metropolitan cities like London are practically non-existent. It is nothing for a big, p schoolboy to elbow an elderly woman aside in the dash for the last remaining seat on the tube or bus, much less stand up and offer his seat to her, as he ought. In fact, it is saddening to note that if a man does offer his seat to an older woman, it is nearly always a Continental man or one from the older generation.

This question of giving up seats in public transport is much argued about by young men, who say that, since women have claimed equality, they no longer deserve to be treated with courtesy, and that those who go out to work should take their turn in the rat race like anyone else. Women have never claimed to be physically as p as men. Even if it is not agreed, however, that young men should stand up for younger women, the fact remains that courtesy should be shown to the old, the sick and the burdened.

Conditions in travel are really very hard on everyone, we know, but hardship is surely no excuse. Sometimes one wonders what would have been the behavior of these stout young men in a packed refugee train or a train on its way to a prisoner-camp during the war. Would they have considered it only right and their proper due to keep the best places for themselves then

Older people, tired and irritable from a day’s work, are not angels, either--far from it. Many a brisk argument or an insulting quarrel breaks out as the weary queues push and shove each other to get on buses and tubes. One cannot commend this, of course, but one does feel there is just a little more excuse.

If cities are to remain pleasant places to live in at all, however, it seems urgent, not only that communications in transport should be improved, but also that communication between human beings should be kept smooth and polite. All over cities, it seems that people are too tired and too rushed to be polite. Shop assistants won’t bother to assist, taxi drivers shout at each other as they dash dangerously round corners, bus conductors pull the bell before their desperate passengers have had time to get on or off the bus, and so on and so on. It seems to us that it is up to the young and p to do their small part to stop such deterioration.

In the author’s view, the best remedy for coping with the hard conditions in travel in cities would be to()

A. attach significance to the moral education of young people

B. improve the means of transportation and the public morality

C. treat people, be they young and old, with courtesy and sympathy

D. demand that everyone avoid brisk arguments and insulting quarrels