Which of the following is not a correct statement ?

Options

A. Any material can be made amorphous by quenching it's melt (or) freezing it's vapour
B. The melt of an amorphous solid when slowly cooled becomes crystalline
C. Glass melts over a range of temperatures
D. Quartz has irregular chains of` SiO_4` units.

Answer

To determine which of the statements regarding solids is not correct, we will analyze each statement one by one.

### Step 1: Analyze Statement A
**Statement A:** Any material can be made amorphous by quenching its melting or freezing its vapor.

- **Explanation:** Amorphous solids can indeed be formed by rapidly cooling a material from its molten state (quenching). This prevents the atoms from arranging into a regular crystalline structure. Therefore, this statement is **correct**.

### Step 2: Analyze Statement B
**Statement B:** The melt of an amorphous solid when slowly cooled becomes crystalline.

- **Explanation:** When an amorphous solid is melted and then cooled slowly, the atoms have enough time to arrange themselves into a regular pattern, leading to crystallization. Hence, this statement is also **correct**.

### Step 3: Analyze Statement C
**Statement C:** Glass melts over a range of temperature.

- **Explanation:** Glass, being an amorphous solid, does not have a sharp melting point like crystalline solids. Instead, it softens and flows over a range of temperatures. Thus, this statement is **correct**.

### Step 4: Analyze Statement D
**Statement D:** Quartz has an irregular chain of SiO4 units.

- **Explanation:** Quartz has a well-defined crystalline structure where the SiO4 tetrahedra are arranged in a regular pattern. Therefore, this statement is **incorrect**.

### Conclusion
The statement that is not correct is **Statement D**: Quartz has an irregular chain of SiO4 units.

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