Answer:
Na3AlF6 (Sodium hexafluoroaluminate)
Explanation:
Cryolite is a double fluoride of sodium and aluminium, having the chemical formula Na3AlF6.
It is used as a solvent for alumina (Al2O3) in the Hall–Héroult process for the extraction of aluminium, as it lowers the melting point and increases conductivity of the electrolyte.


Electricity is passed through an acidic solution of Cu$^{2+}$ till all the Cu$^{2+}$ was exhausted, leading to the deposition of 300 mg of Cu metal. However, a current of 600 mA was continued to pass through the same solution for another 28 minutes by keeping the total volume of the solution fixed at 200 mL. The total volume of oxygen evolved at STP during the entire process is ___ mL. (Nearest integer)
Given:
$\mathrm{Cu^{2+} + 2e^- \rightarrow Cu(s)}$
$\mathrm{O_2 + 4H^+ + 4e^- \rightarrow 2H_2O}$
Faraday constant = 96500 C mol$^{-1}$
Molar volume at STP = 22.4 L