问题 选择题

下列除杂设计(括号内为杂质)所选用试剂和操作都正确的是(  )

序号物  质选用试剂操作
ACO2(CO)O2点燃
BNaOH溶液(Na2CO3稀盐酸加入试剂至不再产生气泡
CKNO3溶液(KOH)Cu(NO32溶液加入适量的试剂,直接蒸发
D蛋白质固体(蔗糖)H2O、

饱和(NH42SO4溶液

溶解、盐析、过滤、

洗涤、低温干燥

A.A

B.B

C.C

D.D

答案

A、除去二氧化碳中的一氧化碳不能够通氧气点燃,这是因为当二氧化碳(不能燃烧、不能支持燃烧)大量存在时,少量的一氧化碳是不会燃烧的;且除去气体中的气体杂质不能使用气体,否则会引入新的气体杂质,故选项所采取的方法错误.

B、NaOH溶液和Na2CO3均能与稀盐酸反应,不但能把杂质除去,也会把原物质除去,不符合除杂原则,故选项所采取的方法错误.

C、KOH能与Cu(NO32溶液反应生成氢氧化铜沉淀和硝酸钾,应再过滤除去不溶物,故选项所采取的方法错误.

D、向蛋白质中加入水,再加入饱和硫酸铵溶液,析出沉淀,此过程叫做蛋白质的“盐析”,再过滤、洗涤、低温干燥,能除去杂质且没有引入新的杂质,符合除杂原则,故选项所选用试剂和操作都正确.

故选D.

阅读理解

It was three o'clock. A man was walking down a high street in the north of England. He was wearing a dark suit and carrying a suitcase. His name was Terry and he and he had lived away from home for twenty years. In fact he was in prison(监狱),

Terry was feeling totally depressed because everything in his hometown had changed. The park where he used to play was now a car park. The house where he was born had dis appeared and in its place,  ironically(具有讽刺意味地), was a bank. Terry wanted to have a cup of coffee in the old small restaurant where he used to go with his friend after school,   but it had become a fast food restaurant. He entered it,   sat down,   and asked for a cup of coffee. Then he felt sadder when he thought of what he had seen.

While paying for the coffee he found an old ticket in his wallet. It was for a pair of shoes he had taken to be repaired the day before the bank robbery 20 years ago. The shoe repairer was an old man then, so Terry was sure that he must be dead. But when he turned the cor ner of the steet, he couldn't believe his eyes. The shop was still there! And it was the same shoe repairer! He looked about a hundred years old. Terry was so happy! Terry told him that he had lived in Australia for the past twenty years and that he forgot to pick up the shoes before he left England. The shoe repairer disappeared into the back of the shop. After ten minutes he came back.

"Were they dark brown,   Italian shoes,   size 42?"he asked slowly.

"Yes!nsaid Terry,   excitedly.

"I haven't repaired them,”the shoe repairer said slowly. “You can take them tomorrow afternoon. ”

小题1:How long had Terry been away from home?

A.Ten years.

B.Five years.

C.Twenty years.

D.Fifteen years.小题2:Where was Terry before he went back home?   A prison in________.

A.Australia

B.England

C.America

D.London小题3:Why was Terry sent to prison?   Because he________.

A.killed a man

B.hit a woman

C.cheated(欺骗) others-

D.robbed a bank小题4:The words "totally depressed" in the second paragraph(段落) means "________".

A.very happy

B.very unhappy

C.very excited

D.very nervous小题5:What's the best title(标题) for the passage?

A,Some things never change 

B.Everything have changed

C,A kind shoe repairer        

D,A longly man

问答题 简答题