化學 1998 年 DSE、CE 選擇題（第 4 頁）

31.

What is the purpose of adding quicklime (calcium oxide) to soil ?

32.

Which of the following combinations is correct ?

	Sulphur dioxide bleach	Chlorine bleach
	The active ingredient is SO₄²⁻(aq)	The active ingredient is OCl⁻(aq)
	It bleaches by oxidation	It bleaches by reduction
	Its bleaching action is faster	Its bleaching action is slower
	Its bleaching effect is temporary	Its bleaching effect is relatively long-lasting

33.

Consider the following information :

Substance	Melting point / °C	Electrical conductivity at room temperature	Solubility in water
W	−34	poor	slightly soluble
X	44	poor	insoluble
Y	232	good	insoluble
Z	782	poor	very soluble

Which of the above substances exists as a simple molecular solid at room temperature ?

34.

Which of the following substances is / are the main product(s) when a mixture of ammonia and oxygen is passed over red-hot platinum ?

(1)nitrogen

(2)nitrogen monoxide

(3)nitric acid

35.

Which of the following statements concerning cigarette smoking is / are correct ?

(1)Tar in cigarette smoke is addictive.

(2)Nicotine in cigarette smoke causes high blood pressure.

(3)Carbon monoxide in cigarette smoke can be removed by smoking cigarettes with filters.

36.

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

(1)It is a condensation polymer.

(2)It can be remoulded.

(3)It can be used to make packaging material for electrical appliances.

37.

Which of the following experiments would produce sulphur dioxide ?

(1)heating iron pyrites in air

(2)heating a mixture of iron and dilute sulphuric acid

(3)heating a mixture of copper and concentrated sulphuric acid

38.

The diagram below shows a catalytic converter fitted to the exhaust system of a car.

Which of the following pollutants from the car engine undergo reactions in the catalytic converter to produce less harmful products ?

(1)carbon monoxide

(2)hydrocarbons

(3)nitrogen monoxide

39.

Brass is commonly used for making ornaments because

(1)it has an attractive appearance.

(2)it can resist corrosion.

(3)it is softer than copper.

Which of the following combinations is correct ?

40.

Which of the following problems are associated with the excessive use of soapless detergents ?

(1)They can cause skin allergies.

(2)They form foam when discharged into rivers and lakes.

(3)They form scum when discharged into the sea.