化學 1998 年 DSE、CE 選擇題

1.

An element X exists as molecules. X has an atomic number of 7 and a molecule of X has a formula X₂. Which of the following can represent the electronic structure of X₂ ?

2.

The formula for ozone is O₃. If one mole of ozone contains x atoms, how many atoms will one mole of oxygen gas contain ?

3.

Which of the following substances is the main constituent of town gas ?

4.

Questions 4 and 5 refer to the following experiment: The circuit shown below is set up and the solid lead(II) bromide is heated until it becomes molten.

Circuit with electrodes X and Y in solid lead(II) bromide being heated

Which of the following statements concerning the experiment is INCORRECT ?

5.

Questions 4 and 5 refer to the following experiment: The circuit shown below is set up and the solid lead(II) bromide is heated until it becomes molten.

Which of the following can be deduced from the experimental results ?

6.

A part of the Periodic Table is shown below.

Part of the Periodic Table with elements a, b, c, d and e

Which of the following statements is correct ?

7.

Which of the following environmental problems is NOT caused by excessive burning of fossil fuels ?

8.

Monosodium glutamate is used

9.

Which of the following substances has a pH less than 7 ?

10.

The formula for hydrated iron(II) sulphate is FeSO₄·xH₂O. On strong heating, 20.1 g of the sulphate produces 9.1 g of water. What is the value of x ? (Relative atomic masses : H = 1.0, O = 16.0, S = 32.1, Fe = 56.0)