Explain the phenomena of itching of glass

Explanation

### Step-by-Step Solution

1. **Understanding Glass Composition**:
- Glass is primarily composed of silicon dioxide (SiO2), along with other oxides such as sodium oxide (Na2O), potassium oxide (K2O), calcium oxide (CaO), barium oxide (BaO), zinc oxide (ZnO), or lead oxide (PbO). The general formula can be represented as R2O·MO·SiO2, where R represents alkali metals and M represents alkaline earth metals.

2. **Introduction to Hydrogen Fluoride (HF)**:
- Hydrogen fluoride is a highly reactive compound that can attack the silicon dioxide present in glass.

...