The melting points of Cu, Ag and Au follow the order

Options

A. `Cu gt Ag gt Au`
B. Cu gt Au gt Ag
C. Au gt Ag gt Cu
D. Ag gt Au gt Cu

Answer

To determine the order of melting points for Copper (Cu), Silver (Ag), and Gold (Au), we need to analyze their electronic configurations and the factors affecting their metallic character and melting points.

### Step-by-Step Solution:

1. **Identify the Electronic Configurations**:
- Copper (Cu): \( [Ar] 3d^{10} 4s^1 \)
- Silver (Ag): \( [Kr] 4d^{10} 5s^1 \)
- Gold (Au): \( [Xe] 4f^{14} 5d^{10} 6s^1 \)

2. **Understand the Trend in Metallic Character**:
- As we move down a group in the periodic table, the size of the elements increases, and the metallic character generally increases as well. However, in this case, we need to consider the lanthanide contraction.

3. **Consider the Effect of Lanthanide Contraction**:
- Lanthanide contraction refers to the phenomenon where the size of the elements does not increase as much as expected due to the filling of f-orbitals. This results in the atomic size of Gold (Au) being similar to that of Silver (Ag), despite being lower in the periodic table.

4. **Analyze the Nuclear Charge**:
- Gold (Au) has a higher nuclear charge (more protons) compared to Silver (Ag). This increased nuclear charge leads to stronger metallic bonding in Gold, despite the similar size due to lanthanide contraction.

5. **Determine the Order of Metallic Character**:
- Based on the above points, the order of metallic character is:
- Copper (Cu) > Gold (Au) > Silver (Ag)
- This order indicates that Copper has the highest metallic character, followed by Gold, and then Silver.

6. **Relate Metallic Character to Melting Points**:
- The melting points of metals are generally higher for metals with greater metallic character due to stronger metallic bonds. Therefore, the order of melting points will follow the same trend as the metallic character:
- Melting Point Order: Copper (Cu) > Gold (Au) > Silver (Ag)

### Final Answer:
The melting points of Cu, Ag, and Au follow the order:
**Cu > Au > Ag**