The metal with exceptionally low melting point is:

Options

A. potassium
B. copper
C. calcium
D. aluminium

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Question:**
The question asks for a metal with an exceptionally low melting point. Generally, metals have high melting points, often around 1000 degrees Celsius.

2. **Identifying the Group of Metals:**
Among metals, alkali metals (the metals in Group 1 of the periodic table) are known for having low melting points compared to other metals.

3. **Properties of Alkali Metals:**
Alkali metals are characterized by having one electron in their outer shell. This results in weaker metallic bonding compared to other metals, which contributes to their lower melting points.

4. **Comparing Options:**
The options provided are:
- Potassium
- Copper
- Calcium
- Aluminium

5. **Analyzing Each Option:**
- **Potassium:** Has a melting point of approximately 63.5 degrees Celsius.
- **Copper:** Has a much higher melting point (around 1085 degrees Celsius).
- **Calcium:** Also has a higher melting point (around 842 degrees Celsius).
- **Aluminium:** Has a melting point of about 660 degrees Celsius.

6. **Conclusion:**
Among the options, Potassium has the lowest melting point, making it the correct answer to the question.

**Final Answer:**
The metal with an exceptionally low melting point is **Potassium**.

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