chem about metal kk

用戶209869

2012-04-30 2:26 am

1. Which of the following statements is/are correct?(1) Tin is more resistant to corrosion than iron.(2) The corrosion of copper is called rusting.(3) Corrosion is the slow process(過程)in which an exposed(暴露) metal is broken down into smaller pieces.A. (1) only B. (2) onlyC. (1) and (3) only D. (2) and (3) only 2. Rusting is the slowest when iron is connected toA. zinc. B. magnesium.C. tin. D. copper. 4. Food cans are tin-plated instead of galvanized because(1) tin is more reactive than zinc so that it protects iron better than zinc.(2) tin ions are non-toxic while zinc ions are toxic.(3) zinc is more expensive than tin.A. (1) only B. (2) onlyC. (1) and (3) only D. (2) and (3) only 5. Which of the following can protect iron from rusting?(1) Iron is alloyed with carbon. (2) Iron is coated with zinc.(3) Iron is connected to copper.A. (1) only B. (2) onlyC. (1) and (3) only D. (2) and (3) only 6. Which of the following processes can be used to slow down rusing of an iron nail?(1) Attaching a piece of magnesium to the iron nail(2) Wrapping a lead wire around the iron nail(3) Putting the nail in paraffin oil(石蠟油)A. (1) only B. (2) onlyC. (1) and (3) only D. (2) and (3) only 7. Iron cans can be protected from rusting by tin-plating because(1) tin protects iron from exposure to air.(2) tin protects iron from rusting by sacrificial protection(3) tin and iron form an alloy which is corrosion resistant.A. (1) only B. (1) and (2) onlyC. (2) and (3) only D. (1) and (3) only 8. Rusting requires the exposure of iron to(1) water. (2) oxygen. (3) salt.A. (1) and (2) only B. (1) and (3) onlyC. (2) and (3) only D. (1), (2) and (3)

回答 (1)

fooks

2012-04-30 8:43 am

✔ 最佳答案

1.
The answer is : A.(1) only

(1) is correct.
(2) is incorrect. Only the corrosion is iron is called rusting.
(3) is incorrect. Corrosion is the slow reaction of iron with water, oxygen orother substances in our environment.

2.
The answer is : B.magnesium

Magnesium is most reactive metal (highest positionin electrochemical series) in the question. Magnesium has the greatest tendencyto release electrons to iron. Therefore, magnesium has the greatest tendency tocorrode first and thus iron is hardly to rust.

4.
The answer is : B. (2) only

(1) is incorrect. Tin is less reactive than zinc.
(2) is correct.
(3) is incorrect. Tin is more expensive than zinc.

5.
The answer is : B. (2) only

(1) is incorrect. Iron is alloyed with carbon to form steel. Steel would rust.
(2) is correct. This is call galvanization.
(3) is incorrect. As copper is less reactive than iron, the iron will rust morereadily.

6.
The answer is : C. (1) and (3) only

(1) is correct. Magnesium is more reactive than iron, and the process is calledsacrificial protection.
(2) is incorrect. As lead is less reactive than iron, the iron will rust morereadily.
(3) is correct. This will keep the iron away from air and water.

7.
The answer is : A. (1) only

(1) is correct.
(2) is incorrect. Tin is less reactive than iron. As the tin layer is scratched,iron will rust rapidly.
(3) is incorrect. Alloy is the homogeneous mixture of iron and otherelement(s). Tin-plating does not form alloy.

8.
The answer is : (A) (1) and (2) only

Water and oxygen mustbe needed in rusting.
Salt makes rusting more rapidly. In the absence of salt, rusting occurs lessrapidly.

參考: fooks

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