问题 选择题

在电解食盐水之前,需要提纯食盐水。为了除去粗盐中的Ca2、Mg2、SO42及泥沙,可将粗盐溶于水,然后进行下 * * 项操作,正确的操作顺序是               (  )

①过滤                ②加过量的NaOH溶液     ③加适量的盐酸 

④加过量的碳酸钠溶液 ⑤加过量的氯化钡溶液

A.①④②⑤③

B.④①②⑤③

C.②⑤④①③

D.⑤④②③①

答案

答案:C

题目分析:在粗盐提纯时,要先除SO42-、Mg2+再除Ca2+,然后过滤最后加适量的盐酸调节,所以正确的操作顺序为②⑤④①③,答案选C。

点评:本题SO42-、Mg2+除去的顺序可以颠倒。

单项选择题
填空题

What’s in a surname You may ask. A new website project has been released, that helps you (1) . Have you ever wondered why your ancestors gathered where they did, or where others with your surname live now A research project (2) in Britain answers these questions. And another study has found the surnames are (3) .
"Smith", for example, remains the most common surname in Britain. Used by (4) people, it has exactly the same concentration it always did in Lerwick, in the Scottish Shetland Islands. "Jones" is (5) , and is the most common among hill farmers (6) .
The data used for this project comes partly (7) . A number of other files are held by Expairing, which is probably Britain’s (8) .
There’ re some of us who are fairly predictable. "Campbell", for example, as you might expect, is somewhat concentrated (9) , and it appears really bizarre to be found anywhere else.
Well, with 25,000 names as (10) , what you can do is put them in general categories, if, for example, you look at (11) . Like the name Webber, you might find it is much more common in the Midlands than (12) . If you go to Wales, most people get their names (13) . And in Yorkshire for example, a lot of people have names (14) that they originally lived in or at least their ancestors did.
Well, we only have 25, 000 names on this website, but there’re (15) now found in Britain and they’ re particularly interesting, for (16) . Most British names are fairly common. And about what we can now do as such is look for (17) from different parts of the world and different faiths, (18) . And what there is in names is actually extremely useful, for researchers in (19) may find a lot about (20) now living in this country.

What’s in a surname You may ask. A new website project has been released, that helps you (1) . Have you ever wondered why your ancestors gathered where they did, or where others with your surname live now A research project (2) in Britain answers these questions. And another study has found the surnames are (3) .
"Smith", for example, remains the most common surname in Britain. Used by (4) people, it has exactly the same concentration it always did in Lerwick, in the Scottish Shetland Islands. "Jones" is (5) , and is the most common among hill farmers (6) .
The data used for this project comes partly (7) . A number of other files are held by Expairing, which is probably Britain’s (8) .
There’ re some of us who are fairly predictable. "Campbell", for example, as you might expect, is somewhat concentrated (9) , and it appears really bizarre to be found anywhere else.
Well, with 25,000 names as (10) , what you can do is put them in general categories, if, for example, you look at (11) . Like the name Webber, you might find it is much more common in the Midlands than (12) . If you go to Wales, most people get their names (13) . And in Yorkshire for example, a lot of people have names (14) that they originally lived in or at least their ancestors did.
Well, we only have 25, 000 names on this website, but there’re (15) now found in Britain and they’ re particularly interesting, for (16) . Most British names are fairly common. And about what we can now do as such is look for (17) from different parts of the world and different faiths, (18) . And what there is in names is actually extremely useful, for researchers in (19) may find a lot about (20) now living in this country.