Hydrofluroic acid can't be stored in glass vessels because it attacks glass to from

Options

A. `Na_(2)SiO_(3)`
B. `Na_(2)SiF_(6)`
C. `SiF_(6)`
D. `SiF_(4)`

Answer

B

Explanation

Gaseous `HF` is very toxic, and should be handled only in a good fume cupboard.Aqueous solutions of `HF` are called hydrofluoride acid.It is very corrosive,even though it is a weak acid.
Hydrofluoride acid is normally handled in metal apparatus made of copper of Monel ,and is always stored in plastic bottles, because it is one of the few substances to attacks glass. The reaction with glass produces the hexafluorosilicate ion ,`SiF_(6)^(2-)`:
`SiO_(2)(s)+6HF(aq.)rarr SiF_(6)^(2-)(aq.)+2H^(+)(aq.)+2H_(2)O(l)`
This property is used in the etching of glass. An object to be etched is dipped in molten wax, and the wax is allowed to harden. the required pattern is then cut through the wax layer. dipping the glass in hydrofluoric acid enables the hydrofluric acid to react with only those parts of the glass surface that are exposed. After a suitable depth glass has been dissolved, the object is removed from the acid bath, rinsed with water, and the wax melted off leaving the glass with the desired etched pattern.