化學 2004 年 DSE、CE 選擇題（第 4 頁）

31.

After heavy rain, the Air Pollution Index becomes lower. Which of the following air pollutants are likely to have been removed by the rain water?

(1)particulates

(2)carbon monoxide

(3)nitrogen dioxide

32.

A counterfeit gold coin is made from an alloy of copper and zinc. Which of the following methods can be used to show that the coin is NOT made of pure gold ?

(1)determining its density

(2)treating it with dilute nitric acid

(3)treating it with dilute hydrochloric acid

33.

Which of the following gases can act as reducing agents ?

(1)ammonia

(2)hydrogen

(3)fluorine

34.

Consider the chemical cell shown below:

Which of the following statements concerning the cell are correct ?

(1)Electrons flow from electrode X to electrode Y in the external circuit.

(2)Oxidation occurs at electrode Y.

(3)A blue colour appears in the KI(aq) after the cell has operated for some time.

35.

Which of the following statements concerning polyvinyl chloride (PVC) are correct?

(1)PVC is used in making raincoats.

(2)PVC softens upon gentle heating.

(3)When PVC is strongly heated, fumes with an irritating odour are emitted.

36.

In which of the following processes would hydrogen be produced ?

(1)electrolysis of an aqueous solution of potassium bromide

(2)passing steam over heated iron powder

(3)adding zinc granules to dilute ethanoic acid.

37.

When solid acid is added to an aqueous solution of sodium hydrogencarbonate, the mixture fizzes. Which of the following ions/ compounds are responsible for the fizz?

(1)sodium ions

(2)hydrogencarbonate ions

(3)citric acid

(4)water

38.

For each of the following questions, decide whether each of the two statements is true or false. If both are true, decide whether the second correctly explains the first.

A.Both statements are true and the 2nd statement is a correct explanation of the 1st statement.

B.Both statements are true but the 2nd statement is NOT a correct explanation of the 1st statement.

C.The 1st statement is false but the 2nd statement is true.

D.Both statements are false.

1st statement	2nd statement
Both but-1-ene and but-2-ene can decolourize a solution of bromine in 1,1,1-trichloroethane.	Both but-1-ene and but-2-ene have the same molecular formula.

39.

For each of the following questions, decide whether each of the two statements is true or false. If both are true, decide whether the second correctly explains the first.

A.Both statements are true and the 2nd statement is a correct explanation of the 1st statement.

B.Both statements are true but the 2nd statement is NOT a correct explanation of the 1st statement.

C.The 1st statement is false but the 2nd statement is true.

D.Both statements are false.

1st statement	2nd statement
Methanoic acid is a non-electrolyte.	Methanoic acid is a covalent compound.

40.

For each of the following questions, decide whether each of the two statements is true or false. If both are true, decide whether the second correctly explains the first.

A.Both statements are true and the 2nd statement is a correct explanation of the 1st statement.

B.Both statements are true but the 2nd statement is NOT a correct explanation of the 1st statement.

C.The 1st statement is false but the 2nd statement is true.

D.Both statements are false.

1st statement	2nd statement
Lead can displace iron from iron(II) nitrate solution.	Lead occupies a higher position in the electrochemical series than iron.