化學 2003 年 DSE、CE 選擇題（第 3 頁）

21.

20.0 cm³ of 2.0 M aqueous ammonia required 16.0 cm³ of sulphuric acid for complete neutralization. What is the concentration for the sulphuric acid? (Relative atomic masses: H = 1.0, O = 16.0, S = 32.1)

22.

Which of the following gases contains the greatest number of molecules ? (Relative atomic masses: H = 1.0, C = 12.0, O = 16.0, Ne = 20.2, Cl = 35.5)

23.

A detergent has the structure shown below:

Which of the following statements concerning this detergent is correct ?

24.

40 cm³ of 2 M hydrochloric acid was mixed with 40 cm³ of 2 M sodium hydroxide solution in a polystyrene cup and the maximum rise in temperature was recorded. Which of the following pairs of solutions, upon mixing, would produce a similar rise in temperature?

25.

Propene is an unsaturated hydrocarbon. Which of the following reactions is/are characteristic of the unsaturated nature of propene?

(1)It undergoes incomplete combustion to give carbon monoxide.

(2)It decolourizes acidified potassium permanganate solution.

(3)It undergoes polymerization to give polypropene.

26.

Ethane reacts with bromine under suitable conditions. Which of the following statements concerning this reaction is/are correct?

(1)The reaction occurs readily in the dark.

(2)The reaction is a substitution.

(3)The reaction gives a mixture of organic products.

27.

Which of the following is/are advantage(s) of using alkaline cells over zinc-carbon cells in cassette players ?

(1)Alkaline manganese cells have longer life time.

(2)Alkaline manganese cells are rechargeable.

(3)Alkaline manganese cells give a more steady voltage over discharge.

28.

Which of the following statements concerning thermoplastics is/are correct?

(1)They soften upon heating.

(2)They are cross-linked polymers.

(3)They are addition polymers.

29.

The structure of two organic compounds are shown below:

Which of the following statements concerning these two compounds is/are correct?

(1)They have the same relative molecular mass.

(2)They have the same chemical properties.

(3)They are both soluble in water.

30.

Iron pyrite (FeS₂) looks like gold and its common name is "fool's gold". Which of the following methods can be used to distinguish iron pyrite from gold ?

(1)comparing their densities

(2)comparing their electrical conductivity

(3)comparing the effect of heat on them