问题 选择题

下图是对四个实验绘制的图象,其中实验结果与图象对应正确的是(  )

A.某温度下,向一定量接近饱和的硝酸钾溶液中不断加入硝酸钾晶体

B.将稀H2SO4滴入一定量的BaCl2溶液中

C.将一定质量的氯酸钾和二氧化锰放入试管中充分加热

D.向pH=13的NaOH溶液中加水稀释

答案

A、变化曲线表明,随着硝酸钾晶体的不断加入,溶液的质量分数不断增大,到了一定程度,该溶液的质量分数保持不变,此变化与事实相符,故A选项正确;

B、变化曲线表明,随着稀硫酸的不断加入,沉淀量不断增加;当稀硫酸过量时,沉淀就会溶解直至消失,此变化与事实不相符;故B选项错误;

C、变化曲线表明,氯酸钾与二氧化锰混合加热时,一开始固体质量就减少了,即氧气开始生成;此变化与事实不相符;故C选项错误;

D、变化曲线表明,PH=13属碱性溶液,加水稀释碱性减弱,以至于变为酸性溶液;此变化与事实不相符;故D选项错误;

故选A.

阅读理解

阅读理解。

     Today anyone will accept money in exchange for goods and services. People use money to buy food,

furniture, books, bicycles and hundreds of other things they need or want. When they work, they usually get

paid in money.

     Most of the money today is made of metal or paper. But people used to use all kinds of things as money.

One of the first kinds of money was shells.

     Shells were not the only things used as money. In China, cloth and knives were used. In the Phillipine

Islands, rice was used as money for a long time. Elephant tusks, monkey tails and salt were used as money in

parts of Africa.

     The first metal coins were made in China. They were round and had a square hole in the centre. People

strung (串联) them together and carried them from place to place.

     Different countries have used different metals and designs for their money. The first coins in England

were made of tin (锡). Sweden and Russia used copper (铜) to make their money. Later some countries began

to make coins of gold and silver.

     But even gold and silver were inconvenient if you had to buy something expensive. Again the Chinese

thought of a way to improve money. They began to use paper money. The first paper money looked more like

note from one person to another than the paper money used today.

     Money has had an interesting history from the days of shell money until today.

1. In the Philippines Islands _____ was once used as money.

A. rice

B. knife

C. cloth

D. wheat

2. What was the first used as money? 

A. Elephants tusks

B. Cloth

C. Salt

D. Shells

3. The first metal coins looked like _____.

A. square-shaped with some designs on them

B. square-shaped with a round hole in the center

C. round-shaped with a square hole in the middle

D. round-shaped with a round hole in the middle

4. The first paper money ______.

A. was passed from west Asia to China

B. looked like a note used today

C. was first used in Europe

D. looked like a piece of fur

5. We can infer from the passage that _____.

A. paper money isn't difficult to make

B. money must be suited to carry

C. people need money to exchange goods with each other

D. people prefer metal coins to paper notes

问答题