化學 1999 年 DSE、CE 選擇題（第 4 頁）

31.

Which of the following metal oxides CANNOT be reduced by heating with carbon ?

(1)magnesium oxide

(2)lead(II) oxide

(3)iron(III) oxide

32.

Which of the following substances can react with acidified potassium permanganate solution ?

(1)ethene

(2)copper(II) sulphate solution

(3)iron(II) sulphate solution

33.

Which of the following reactions will occur when aluminium powder is added to silver nitrate solution ?

(1)displacement

(2)anodization

(3)redox

34.

Iodine is a solid at room temperature and pressure. Which of the following statements concerning the structure of iodine is/are correct ?

(1)Iodine has a giant covalent structure.

(2)Iodine molecules are held together by van der Waals’ forces.

(3)Iodine atoms are held together in pairs by covalent bonds.

35.

The label below is displayed on a container for chemical X :

Which of the following chemicals may X be ?

(1)bromochlorodifluoromethane

(2)ethanol

(3)potassium

36.

The equation below represents the reaction of chlorine with hot concentrated potassium hydroxide solution :

3Cl₂(g) + 6KOH(aq) → 5KCl(aq) + KClO₃(aq) + 3H₂O(ℓ)

Which of the following statements concerning this reaction is/are correct ?

(1)Potassium hydroxide acts as a reducing agent.

(2)The oxidation number of chlorine changes from 0 to –1.

(3)The oxidation number of chlorine changes from 0 to +5.

37.

Which of the following substances can react with magnesium to give a colourless gas which burns with a ‘pop’ sound ?

(1)grapefruit juice

(2)citric acid crystals

(3)household bleach

38.

Which of the following reagents is/are commonly stored in brown bottles ?

(1)potassium permanganate solution

(2)concentrated sulphuric acid

(3)concentrated nitric acid

39.

Element X has an isotope ³¹₁₅X. Which of the following statements is/are correct ?

(1)X belongs to Group V of the Periodic Table.

(2)X can react with oxygen to form an ionic compound.

(3)³¹₁₅X has 16 neutrons.

40.

Consider the following chemical cell :

Which of the following changes would lead to an increase in the voltage of the cell ?

(1)The zinc electrode is replaced with a magnesium electrode.

(2)The copper electrode is replaced with an iron electrode.

(3)The sodium chloride solution is replaced with a sugar solution.