Q. When sand is heated with hydrofluoric acid and a wet rod is brought in contact with vapours evolving a white deposit is due to
A) $SiF_{4}$
B) $SiF_{2}$
C) $H_{4}SiO_{4}$
D) None of these
Explanation
(c)
Sand, on heating with HF, give silicon tetrafluoride vapours, which form silicic acid $(H_{4}SiO_{4})$, on coming in contact with water.
$\ \ \ \ \ SiO_{2} + 4HF \rightarrow SiF_{4} + 2H_{2}O$
$3SiF_{4} + 4H_{2}O \rightarrow 2H_{2}SiF_{6} + H_{4}SiO_{4}$
white
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.