问题 选择题

下列试剂能一次鉴别出稀盐酸、澄清石灰水、氢氧化钠溶液的是

A.紫色石蕊试液

B.酚酞试液

C.碳酸钙粉末

D.碳酸钾溶液

答案

答案:D

题目分析:A稀盐酸可使石蕊试液变红;澄清石灰水与氢氧化钠溶液均呈碱性,滴入紫色石蕊试液均使其变蓝,无法区分二者,此项不正确。B澄清石灰水与氢氧化钠溶液均呈碱性,滴入酚酞均使酚酞变红,无法区分二者,此项不正确。C碳酸钙可与稀盐酸反应有气泡生成,与另两种物质不反应,无法进行一次性鉴别。此项不正确。D稀盐酸可与碳酸钾反应生成二氧化碳气体,观察到有气泡生成;澄清石灰水不的氢氧化钙可与碳酸钾反应形成白色的沉淀碳酸钙;氢氧化钠与碳酸钾不反应,无明显变化。可区分三种物质,此项正确。所以应选D项。

单项选择题
阅读理解

D

To us it seems so natural to put up an umbrella to keep the water off when it rains.But actually the umbrella was not invented as protection against rain.Its first use was as a shade against the sun.

Nobody knows who first invented it, but the umbrella was used in very ancient times.Probably the Chinese were the earliest to use it in the eleventh century BC.We know that the umbrella was used in ancient Egypt and Babylon as a sunshade.And there was a strange thing connected with its use: it became a symbol of honor and authority.In the Far East in ancient times, the umbrella was allowed to be used only by royalty or by those in high offices.

In Europe, the Greeks were the earliest to use the umbrella as a sunshade.And the umbrella was allowed in common use in ancient Greece.But it is believed that the earliest persons in Europe to use the umbrella as protection against rain were the ancient Romans.

During the Middle Ages, the use of the umbrella practically disappeared.Then it appeared again in Italy in the late sixteenth century.And again, it was considered a symbol of power and authority.In around 1680, the umbrella appeared in France and later on in England.

By the eighteenth century, the umbrella was used against rain throughout most of Europe.Umbrellas have not changed much in style during all this time, though they have become  much lighter in weight.It wasn’t until the twentieth century that women’s umbrellas began to be made in a whole variety of colors.

小题1:The first use of umbrella was as ______________.

A.protection against rain

B.shade against the sun

C.a symbol of power and authority

D.a symbol of honor and authority小题2:In Europe, the umbrella was first used against rain ___________.

A.in Greece

B.in Rome

C.in England

D.in France小题3:From the text, we can infer that _________.

A.the umbrella changed much in style in the eighteenth century.

B.no one knows why the umbrella was used in very ancient times.

C.once ordinary people had no right to use umbrellas.

D.during the Middle Ages the umbrella was common in Europe.小题4:This passage talks mainly about ____________.

A.when and how the umbrella was invented.

B.why the umbrella was so popular in Europe.

C.the development of the umbrella.

D.the history and use of the umbrella.