Which of the following is considered as true amorphous solid

Options

A. `NaCl`
B. `CuSO_(4).5H_(2)O`
C. `NaCl & KCl`
D. Gelatinous `Al(OH)_(5)`

Answer

To determine which of the given options is considered a true amorphous solid, we need to understand the characteristics of amorphous solids and differentiate them from crystalline solids.

### Step-by-Step Solution:

1. **Define Amorphous Solids**:
Amorphous solids are non-crystalline materials that lack a long-range order in their atomic arrangement. Unlike crystalline solids, they do not have a definite geometric shape or a well-defined melting point.

**Hint**: Remember that amorphous solids do not have a regular arrangement of particles.

2. **List the Given Options**:
The options provided are:
- Sodium chloride (NaCl)
- Copper sulfate pentahydrate (CuSO₄·5H₂O)
- Potassium chloride (KCl)
- Gelatinous aluminium hydroxide (Al(OH)₃)

**Hint**: Write down the names of the compounds to analyze their properties.

3. **Identify Crystalline Solids**:
- **Sodium chloride**: This is a well-known crystalline solid that forms a regular cubic lattice structure.
- **Copper sulfate pentahydrate**: This compound also forms a crystalline structure, typically in the form of blue crystals.
- **Potassium chloride**: Similar to sodium chloride, it forms a regular crystalline structure.

**Hint**: Look for compounds that have a regular geometric arrangement.

4. **Identify the Amorphous Solid**:
- **Gelatinous aluminium hydroxide**: This substance does not have a definite geometric structure and is typically found in a gel-like form, which is characteristic of amorphous solids.

**Hint**: Consider the physical state and structure of the substances to identify the amorphous one.

5. **Conclusion**:
Based on the analysis, the only true amorphous solid among the options provided is **gelatinous aluminium hydroxide**.

**Final Answer**: Gelatinous aluminium hydroxide is considered a true amorphous solid.