化學 2006 年 DSE、CE 選擇題（第 4 頁）

31.

Consider the conversions between three nitrogen compounds shown in the flow diagram below:

Which of the following statements is correct ?

32.

Which of the following solutions when mixed with 50.0 cm³ of 1.0 M hydrochloric acid would NOT result in a change in pH?

33.

The set-up below shows a chemical cell connected to a voltmeter:

In the set-up, electrons flow in such a direction that the concentration of Cu²⁺(aq) ions in each half cell becomes the same eventually. Which of the following statements concerning the set-up is correct ?

34.

Metal X forms an oxide with the formula X₂O. Upon strong heating, the oxide undergoes decomposition according to the following equation: 2X₂O(s) → 4X(s) + O₂(g) Complete decomposition of 2.90 g of the oxide gives 150 cm³ of oxygen, measured at room temperature and pressure. What is the relative atomic mass of X? (Relative atomic mass: O = 16.0; molar volume of gas at room temperature and pressure = 24 dm³)

35.

Which of the following materials is/are used in the production of soap ?

(1)petroleum fractions

(2)sodium hydroxide

(3)sulphuric acid

36.

The repeating unit of polymer X is shown below:

Which of the following statements about X is/are correct ?

(1)X is an addition polymer.

(2)X is formed from two different monomers.

(3)X is a thermosetting plastic.

37.

Which of the following statements concerning a catalyst are correct?

(1)A catalyst can alter the rate of reaction.

(2)The mass of a catalyst remains unchanged at the end of the reaction.

(3)A catalyst should be in the same physical state as the reaction.

38.

In an experiment to prepare a polymer, equal volumes of styrene and kerosene are mixed and then heated under reflux for about an hour. After cooling, the resulting mixture is poured into a large volume of methanol. A white waxy solid is formed. Which of the following statements concerning the experiment are correct?

(1)The experiment should be conducted in a fume cupboard.

(2)The mixture of styrene and kerosene is heated under reflux because kerosene is volatile.

(3)Methanol reacts with styrene to form the waxy solid.

39.

There are two unlabeled bottles in the laboratory. One of the bottles contains an aqueous solution of common salt and the other contains antiseptic alcohol. Which of the following methods can be used to distinguish the substances in the bottles?

(1)adding a small amount of water

(2)detecting their odour

(3)measuring their electrical conductivity

40.

In a titration experiment, which of the following apparatus should be rinsed with the solution it is about to contain?

(1)burette

(2)pipette

(3)conical flask