1995 年
化學 · 共 49 題 · 點擊選項即時核對答案
The atomic number of an element X is 18. An atom of X has a mass number of 40. The atom has
The electronic structure of a compound formed between an element X and chlorine is shown below.
(only electrons in the outermost shells are shown.) What would be the formula of the compound formed between X and magnesium?
Which of the following correctly describes the structure of quartz?
Boron consists of two isotopes. The table below lists the relative abundance of these two isotopes.
| Isotope | Relative abundance |
|---|---|
| ¹⁰₅B | 19.7% |
| ¹¹₅B | 80.3% |
The relative atomic mass of boron (correct to 1 decimal place) is
Which of the following methods can be used to extract lead from lead(II) oxide?
Which of the following fertilisers contains the largest percentage by mass of nitrogen? (Relative atomic masses : H = 1.0, N = 14.0, O = 16.0, Na = 23.0, S = 32.0, Cl = 35.5, K = 39.0)
Which of the following substances, when mixed, would undergo a chemical reaction?
In order to prepare 250 cm³ of 0.10 M sodium hydroxide solution from 1.0 M sodium hydroxide solution, which of the following combinations of apparatus should be used?
A student performed a titration in which he added an acid from a burette to an alkali contained in a conical flask. The following diagrams show the initial and final readings of the burette.
What was the volume of the acid added from the burette to the conical flask?
In which of the following equations does the underlined substance become reduced?