问题 填空题

分别将Na2O、NaCl、SO3溶于水,依次得到A、B、C三种溶液,它们的pH由大到小的顺序为(用A、B、C表示,下同)______,分别向这三种溶液中滴入紫色石蕊试液后显红色的是______溶液.

答案

Na2O溶于水能与水反应生成氢氧化钠,水溶液呈碱性,pH大于7,氯化钠的水溶液呈中性,pH等于7,三氧化硫与水反应生成硫酸,呈酸性,pH小于7,能使石蕊试液变红,故填:ABC、C.

单项选择题
阅读理解

阅读表达。

阅读下面短文,并根据短文后的要求答题(请注意问题后的字数要求)。

     If the sun has enough power to warm and light the whole earth, it must have enough power to do other

things, too. Can we use the sun's abundant energy to supply electricity,or at least to perform the functions

which electricity or other types of power usually perform? The answer is yes.

      For example, people have been using the reflected heat of the sun to cook for many years. Solar cookers

have been built with several curved mirrors reflecting the sun and focusing its heat on the cooking component.

This equipment can be used just like a gas or electric stove: it is more expensive to make but it does not need

any fuel. So costs nothing to use. Another possibility of using solar energy is in house heating.

      The form of energy we use most is electricity, and every day more is needed. But electricity has to be

made, too, and to make it, are required-oil, gas and nowadays even uranium(铀).

     The question which worries everyone today is: how long will these fuels last? Nobody knows it for sure,

but most experts think it will soon be difficult to obtain sufficient electricity from these sources. It is possible

that the sun can make a contribution here, too.

     Solar power has already been used to produce terrific heat. In Southern France a solar furnace( huge

stove) has been built, where temperatures reach more than 3,000 ℃. This furnace is only used for experiments

at present, but could be used to produce steam for a power station.

1. What is the main idea of the passage? ( Please answer within 10 words. )

_______________________________________________________________________________________

2. Which sentence in the passage can he replaced by the following one?

    The sun can also make it possible for us to get a large quantity of electricity instead of from other fuels.

_________________________________________________________________________________________

3. Please fill in the blank in the passage with proper words or phrases to complete the sentence.

   ( Please answer within 10 words. )

_________________________________________________________________________________________

4. Which can last longer, the ordinary fuels or the solar energy? What shall we do to have enough electricity?

    ( Please answer within 30 words. )

________________________________________________________________________________________

5. Translate the underlined sentence in the passage into Chinese.

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