Acid used for making permanent marking on the glass surface is: — p Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Glass is primarily composed of silica (SiO2) and silicates, which are generally chemically inert to most acids. Step 2: Hydrofluoric acid (HF) is highly unique because it reacts readily with silica to form soluble hexafluorosilicic acid and gaseous silicon tetrafluoride: SiO2 + 4HF -> SiF4 + 2H2O, and SiF4 + 2HF -> H2SiF6. This corrosive action dissolves the glass surface, a process known as glass etching. Step 3: Consequently, HF is the acid used for making permanent markings on glass surfaces. Thus, the correct option is (b).