化學 2009 年 DSE、CE 選擇題（第 5 頁）

41.

Anodised aluminium is more commonly used than iron for making window frames. This is because

(1)the cost for extracting aluminium is lower than the cost for extracting iron.

(2)anodised aluminium is more corrosion resistant than iron.

(3)anodised aluminium is harder than iron.

42.

Which of the following acids can react with silver ?

(1)dilute sulphuric acid

(2)concentrated nitric acid

(3)concentrated hydrochloric acid

43.

Beaker A contains 100 cm³ of 1 M HCl(aq), while beaker B contains 50 cm³ of 2 M HCl(aq). Equal mass of magnesium ribbons are added to the two beakers. Both magnesium ribbons disappear after reaction. Which of the following statements is / are correct ?

(1)The reactions occuring in both beakers have the same initial rate.

(2)Same volume of gas, measured at the same temperature and pressure, is given out in both beakers.

(3)Magnesium chloride solutions of the same concentration are produced in both beakers.

44.

In the electrolysis of a copper(II) sulphate solution using copper cathode and graphite anode, which of the following would change ?

(1)pH of the solution

(2)colour of the solution

(3)mass of the graphite anode

45.

Which of the following statements concerning soapy and soapless detergents are correct ?

(1)They both are emulsifying agents.

(2)They both contain hydrophobic and hydrophilic parts.

(3)Soapy detergent is biodegradable while soapless detergent is non-biodegradable.

46.

Which of the following information is needed in order to deduce the molecular formula of a compound from its empirical formula ?

(1)relative molecular mass of the compound

(2)percentage by mass of each constituent element

(3)relative atomic mass of each constituent element

47.

Which of the following statements concerning the anodisation of an aluminium object are correct ?

(1)The electrolyte used can be dilute sulphuric acid.

(2)A layer of aluminium oxide is formed on the surface of the object.

(3)The aluminium object should be connected to the negative terminal of the power supply.

48.

For Questions 48–50, 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 are true and the second correctly explains the first.

B.Both are true but the second does not correctly explain the first.

C.The first is false but the second is true.

D.Both are false.

1st statement	2nd statement
All salt solutions are neutral.	All salts are formed from neutralisation.

49.

For Questions 48–50, 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 are true and the second correctly explains the first.

B.Both are true but the second does not correctly explain the first.

C.The first is false but the second is true.

D.Both are false.

1st statement	2nd statement
Sulphates can be oxidised to sulphites.	Oxidation number of sulphur in sulphates is higher than the oxidation number of sulphur in sulphites.

50.

For Questions 48–50, 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 are true and the second correctly explains the first.

B.Both are true but the second does not correctly explain the first.

C.The first is false but the second is true.

D.Both are false.

1st statement	2nd statement
Discharge of synthetic detergents into rivers may cause rapid growth of algae.	Synthetic detergents may contain nutrients for the growth of algae.