化學 1991 年 DSE、CE 選擇題（第 3 頁）

21.

The IUPAC name for

is

22.

Teflon, a polymer used for coating and non-stick cooking utensils, has the structure given below:

Which of the following is the monomer for Teflon?

23.

A sample of polymer gives acid fumes on strong heating. The polymer is probably

24.

Hydrogen peroxide decomposes according to the following equation: 2H₂O₂(aq) → 2H₂O(l) + O₂(g) A student made use of the above reaction to study how the rate of decomposition of 1.0 mole of hydrogen peroxide varied with time. Which of the following graphs is a correct representation of the result?

25.

Propan-1-ol is refluxed with acidified potassium permanganate solution for a long time. Which of the following descriptions is/are correct ?

(1)The reactants undergo esterification.

(2)Propanoic acid is formed.

(3)The permanganate is reduced.

26.

Which of the following substances, when heated, can react with oxygen ?

(1)sodium

(2)sulphur

(3)iron

27.

Which of the following gases contain the same number of molecules as 300 cm³ of oxygen under the same temperature and pressure?

(1)150 cm³ of NH₃

(2)200 cm³ of O₃

(3)300 cm³ of He

(4)300 cm³ of HCl

28.

Which of the following statements is/are true for soapless detergents ?

(1)All soapless detergents are not biodegradable.

(2)Soapless detergents form a scum with sea water.

(3)Soapless detergents are mainly manufactured from products of the petroleum industry.

29.

Which of the following oxidation numbers can nitrogen display in its compounds ?

(1)−3

(2)+2

(3)+3

(4)+4

30.

In an experiment to study the rate of reaction, 100 cm³ of 2 M hydrochloric acid are added to excess zinc granules at room temperature. Which of the following modifications would increase the initial rate of reaction?

(1)The hydrochloric acid is 4 M instead of 2 M.

(2)The volume of hydrochloric acid is 200 cm³ instead of 100 cm³.

(3)The hydrochloric acid is replaced by 100 cm³ of 2 M sulphuric acid.