问题 问答题

浅绿色溶液A和无色溶液B可进行下列反应,D是一种常见的盐,E是气态氢化物,G是非金属氧化物.

(1)填写下列各物质的化学式:A______,B______,H______;

(2)浅绿色溶液A与NaOH溶液反应先生成白色沉淀,此沉淀迅速变成灰绿色最后变成红褐色,写出此反应过程中的化学方程式

①______;

②______.

(3)写出沉淀C与稀盐酸反应生成浅绿色溶液A和气体E的化学方程式:______.

答案

溶液D加入硝酸银后生成沉淀不溶于稀硝酸,应为AgCl,且滤液焰色反应呈黄色,则D为NaCl,G可使品红褪色,应为SO2,则E为H2S,H可与KSCN反应呈红色,则H为FeCl3,A为FeCl2,则B为Na2S,

(1)由以上分析可知A为FeCl2,B为Na2S,H为FeCl3,故答案为:FeCl2;Na2S;FeCl3

(2)浅绿色溶液A与NaOH溶液反应先生成白色沉淀,反应为FeCl2+2NaOH=2NaCl+2Fe(OH) 2↓,此沉淀迅速变成灰绿色最后变成红褐色,反应为4Fe(OH) 2+O2+2H2O=4Fe(OH) 3 ,故答案为:FeCl2+2NaOH=2NaCl+2Fe(OH) 2↓;4Fe(OH) 2+O2+2H2O=4Fe(OH) 3

(3)沉淀C为FeS,可与盐酸反应,反应的化学方程式为FeS+2HCl=FeCl2+H2S↑,故答案为:FeS+2HCl=FeCl2+H2S↑.

判断题
单项选择题

While the ripples of America’s subprime-mortgage crisis have spread far and wide, Latin America—a place long associated with financial disaster—has remained improbably calm. Banks have reported no unpleasant surprises. Brazil and Peru have been blessed with coveted investment-grade ratings. Surprisingly, perhaps the fleetest country of all has been Argentina. Since it emerged from the financial crisis of 2001-02, it has been one of the world’s fastest-growing economies. It is expected to expand faster than most of its neighbors again this year.

Quite simply, it barely has any credit. Back when its economy virtually collapsed, the country suffered a run on its banks, followed by a freeze on withdrawals, and a massive currency devaluation. As a result, bank lending to the private sector shrivelled, from 23.8% of GDP in 2000 to 10.8% in 2003. Since then, it has rebounded to a piddling 13% ; by contrast, the ratio in Brazil was 36.5% in 2006. Almost all of these loans in Argentina are accessible only on a short-term basis.

Once its recovery began in June 2002, Argentina became a paradise for business. Unemployment of over 20% kept wages down, and the devaluation gave exporters an edge on foreign competitors. The ample productive capacity left idle by the crisis meant firms could expand without making big investments. And the windfall profits reaped by agricultural exporters, thanks to record commodities prices, enabled many of them to finance new projects out of earnings. Hence the economy could grow at almost 9% a year with little need for credit.

But such a lucky confluence of factors could not last. Starting in early 2005 ,.inflation picked up, a sign that the installed capacity was starting to limit output. Salaries and prices for raw materials increased sharply, cutting into profits. And farmers were particularly hard hit when the government nearly doubled the taxes in farm exports. Now, just as companies need to embark on big investments if they are to keep growing, their margins are no longer big enough to pay for the expansion and they need to borrow.

So, the time is ripe for the country’s financial system to recover. But a number of things are in the way. Foremost is Argentina’s business risk. Those in the informal economy (which represents over 40% of GDP) can neither save nor borrow legally, lest they become known to the taxmen. The rest remain cowed by memories of the crisis. Although Argentines have poured their savings into property, fuelling a construction boom, they still hold about four-fifths of their deposits abroad.

Inflation, fuelled by a public-spending binge, state-mandated wage increases, and a cheap currency, is not helping either. No one knows how high it is. The consumer-price index is doctored to keep the official rate below 10%, but private estimates suggest it is near 25%. Without a reliable index of inflation, lending is almost impossible, even for the medium term. And the central bank has kept interest rates ply negative in real terms, encouraging workers to spend their wages rather than to save.

It can be inferred from the first paragraph that()

A. Latin America has been greatly influenced by America’s subprime-mortgage crisis

B. Latin America is suffering a financial disaster

C. Argentina has suffered a financial crisis at the beginning of this century

D. Argentina’s economy grows faster than any other countries’ economy