Q17 / 120 · NTA Abhyas (JEE Main) 2020 · Chemistry · p Block Elements (Group 15, 16, 17 & 18)

When a fluoride is heated with concentration $H_{2} S O_{4}$ in a glass tube and if a drop of water is held at the mouth of the glass tube, a white deposit formed is of

A
$H_{2} S i F_{6}$
B
$S i O_{2}$
Correct answer
C
$H_{2} S i O_{3}$
D
$S i F_{4} + H_{2} F_{2}$

Solution

C a F_{2} + \underset{c o n c .}{H_{2} S O_{4}} \to C a S O_{4} + H_{2} F_{2}

S i O_{2} + 2 H_{2} F_{2} \to S i F_{4} + 2 H_{2} O

{3SiF}_{4} + {3H}_{2} O \to \underset{\begin{matrix} Silicic acid \\ (Gelatinous mass) \end{matrix}}{H_{2} {SiO}_{3}} + \underset{\begin{matrix} (Hydrofluoro \\ silicic acid) \end{matrix}}{{2H}_{2} {SiF}_{6}}

Hence, the correct answer is option: 'C'.

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