CIE iGCSE Co-Ordinated Science C2.5 Simple molecules and covalent bonds Exam Style Questions Paper 1
Question
Which statement about a carbon dioxide molecule is correct?
A. It is composed of metallic elements, which are covalently bonded.
B. It is composed of metallic elements, which are ionically bonded.
C. It is composed of non-metallic elements, which are covalently bonded.
D. It is composed of non-metallic elements, which are ionically bonded.
▶️Answer/Explanation
Answer: C
Explanation: Carbon dioxide (CO₂) is composed of non-metallic elements (carbon and oxygen) that are covalently bonded, meaning they share electrons.
Question
Which row describes the properties of a covalent compound?
| Melting Point (°C) | Solubility in Water | Undergoes Electrolysis When Molten |
|---|---|---|
| A. 100 | Insoluble | No |
| B. 110 | Soluble | Yes |
| C. 950 | Insoluble | No |
| D. 2200 | Soluble | Yes |
▶️Answer/Explanation
Answer: A. 100, Insoluble, No
Explanation: Covalent compounds generally have low melting points (e.g., 100°C), are often insoluble in water, and do not conduct electricity or undergo electrolysis when molten.
Question
Which diagram represents molecules of a compound?
▶️Answer/Explanation
Ans : B
Question
The structures of some compounds are shown.
In which rows does the formula match the structure?
A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4
▶️Answer/Explanation
Ans : B