问题 选择题

某同学为试验CuS在不同酸中的溶解性,取4份黑色CuS粉末试样置于试管中,分别加入醋酸、浓盐酸、浓硫酸、浓硝酸溶液.观察到如下现象:①CuS不溶于醋酸溶液;②CuS不溶于浓盐酸;③CuS不溶于浓硫酸;④CuS在浓硝酸中溶解,溶液变蓝,并有红棕色刺激性气体产生.根据上述现象,该同学得出了以下结论,其中正确的是(  )

A.CuS不溶于弱酸,能溶于强酸

B.CuS不溶于非氧化性酸,能溶于氧化性酸

C.CuS溶于硝酸,是因为硝酸氧化性强于硫酸,S2-被氧化,使溶解沉淀平衡往溶解方向移动

D.CuS溶于硝酸,是因为硝酸的酸性大于硫酸和盐酸的酸性,S2-结合H+,放出H2S气体,使溶解沉淀平衡往溶解方向移动

答案

A、CuS不溶于浓硫酸,在浓硝酸中溶解,可以知到硫化铜在强酸浓硫酸中是不溶的,故A错误;

B、浓硫酸、硝酸均是强氧化性的酸,但是硫化铜在强酸浓硫酸中是不溶的,故B错误;

C、CuS溶于硝酸的过程是硫离子被硝酸氧化的过程,S2-被氧化,浓度减小,所以硫化铜的沉淀溶解平衡右移,使得硫化铜溶于硝酸中,故C正确;

D、CuS溶于硝酸的过程是硫离子被硝酸氧化的过程,S2-被氧化,浓度减小,所以硫化铜的沉淀溶解平衡右移,使得硫化铜溶于硝酸中,故D错误.

故选C.

阅读理解

SYDNEY (AFP) — Thousands of people sat down to breakfast on the Sydney Harbor Bridge on Sunday after the bridge was closed to traffic and carpeted with grass for the first time for a giant picnic.

About 6,000 early riser were on the steel bridge from 6:30 am to take part in the two-hour event designed to show Sydney’s best food and outdoor lifestyle.

As music performers provided the background music, those who had won tickets to the picnic in a random lottery (随机抽奖) began to feast on fruit, pastries, muesli, yoghurt ...

“It’s amazing to see the bridge in this perspective (角度),” said Don Fuchs who lives near the bridge, which is used by about 100,000 cars daily.

“Usually you sit in the car, you cross it, and that’s it.”

“It was beautiful,” said Linda Curnow who attended the picnic with her family. “The grass was so thick that it was like being in your backyard.”

New South Wales state Premier Nathan said the event was set to become a mark of an annual Sydney’s month-long October food festival.

About 45,000 people applied for tickets to the breakfast for which people brought their own food but were able to taste samples from some of the state’s best producers.

Organizers used about 40 percent of the grass on Sydney parks. The bridge reopened at about 1:00 pm.

64. What made Linda Curnow feel as if she were in her own backyard?

A. There being no cars passing by.

B. So much food offered by Australian producers.

C. So many people dining at the same time.

D. The thick grass covering the bridge.

65. Why was the event planned?

A. To mark the Sydney food festival.              B. To attract more tourists to Sydney.

C. To promote the Australian life.                   D. To display the world’s best food.

66. We learn from the passage that _____.

A. the giant picnic is organized in a park in Sydney

B. the grass from Sydney parks was moved to the bridge

C. the Sydney Harbour Bridge was open to traffic all day

D. those who had won tickets to the picnic didn’t eat breakfast

67. What would be the best title for the passage?

A. Welcome to Sydney 

B. October — Sydney’s art festival

C. Thousands eat breakfast on Sydney Harbour bridge

D. What is the feature of Sydney?

问答题 简答题