问题 填空题

请你运用化学知识解释生活中的一些现象:

(1)鹅卵石河底比泥河底的河流清澈得多,原因是______;在某些农村常用明矾来净水,其作用是______.

(2)在冬季,人们常看到养鱼池的冰面上打有很多洞,其原因是______

(3)炸油条时,当面团放入油锅后,碳酸氢钠受热分解成碳酸钠、水和二氧化碳,不断产生的二氧化碳会使油条膨胀并浮出油面.该反应类型是______,请用化学方程式表示其中的变化______.

答案

(1)鹅卵石起到过滤作用,所以鹅卵石河底比泥河底的河流清澈得多;明矾溶于水后生成胶状物对杂质的吸附,使杂质沉降,所以农村常用明矾来净水;

故答案为:鹅卵石起到过滤作用;明矾溶于水后生成胶状物对杂质的吸附,使杂质沉降;

(2)养鱼池的冰面上打有很多洞,其原因是增加水中氧气的含量,为鱼类提供充足的氧气(或补充空气);

故填:增加水中氧气的含量,为鱼类提供充足的氧气(或补充空气);

(3)碳酸氢钠受热分解为碳酸钠、二氧化碳和水,是由一种物质分解生成三种物质,属于分解反应;该反应的反应物是碳酸氢钠,生成物是碳酸钠、二氧化碳和水,反应条件是加热,用观察法配平即可,所以方程式为:2NaHCO3 

  △  
.
 
Na2CO3+H2O+CO2↑;

故答案为:分解反应;2NaHCO3 

  △  
.
 
Na2CO3+H2O+CO2↑.

问答题
阅读理解

阅读理解。

     Some of my earliest childhood memories are of the beach-in the hot sun, building sandcastles, burying Dad

in the sand.

     Now the coast has a strangely-pleasant and relaxing attraction. I look forward to a windy clifftop (崖顶)

walk or a rainy day rockpicking just as much as those rare moments when I get to a short sleep in the sun. But

there's nothing more pleasurable than turning up at a beach to find it deserted.

     These are my favorite secret beaches-ones either not well known or take a bit of effort to get to. Most of

those listed scored highly in the Marine Conservation Society Good Beach Guide 2009; the others are too secret

even for them.

     Sennen Cove is just a mile northeast of Land's End, the westernmost point of mainland England. It's a

beautiful spot, with white sands, deep green sea and amazing sunsets over the Isles (群岛) of Scilly, 28 miles

away.

     The west-facing beach is popular with surfers, with bigger waves and winds often found at the Gwenver

end. There's a beach restaurant with good views of the bay and the sunsets.

     The smallest of Isles of Soilly, Bryher is a mile long, half a mile wide-and a natural wilderness of unbelievable

scenery. Walk along the narrow sandy roads to the eastern seaboard and you come to two quiet beaches.

     Green Bay has views over to the palm (棕榈]) trees of Tresco's Abbey Gardens, and a little further south is

Rushy Bay, a beautiful beach facing the deserted island of Samson.

     On Bryher, farm shops sell locally grown produce, and they trust you to leave the money in the pot. It's that

kind of place.

1. According to the passage, which of the following is TRUE?

A. The author is a tourist guide in a tourist agency.

B. The author likes walking on a windy clifftop most.

C. The author wrote the article to advertise for the beaches.

D. The author loves beaches that are not known to most people.

2. Which of the following maps can correctly describe the geography position? (LE= Land's End

    SC= Sennen Cove IS= the Isles of Scilly)

A.  B.  C.  D.

3. From the passage we can know that _____.

A. Bryher is the smallest island in the world

B. Samson is an island on which no man lives

C. Rushy Bay has views over to the palm trees

D. Green Bay is situated to the south of Rushy Bay

4. The best title for the passage is _____.

A. Secret Beaches on the British Isles

B. The Beautiful British Isles

C. The Most Pleasurable Place in Britain

D. My Experience of Searching Beaches