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In Down's process for the manufacture of...

In Down's process for the manufacture of sodium , `CaCl_(2)`, is added to increase its melting point.

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The correct Answer is:
F
`CaCl_(2)` is added to lower the melting point from `1080K(` melting point of `NaCl)` to `850K`. This is due to following reasons `:`
`a.` At such high temperature, it is very difficult to maintain `Na` in the molten state during electrolysis. ltbr. `b.` Moreover, `Na` is volatile at this temperature and a part of it would be vapourize.
`c.` Molten `Na`, gets dispersed in molten `NaCl` to form metallic fog at high temperature. ltbr. `d.` Both `Na` and `Cl_(2)` produced in the electrolysis have a corrosive action on the vessel used.
The over all reaction are as follows `:`
At cathode `: Na^(o+)+e^(-) rarr Na`
At anode `: Cl^(c-)rarr (1)/(2)Cl_(2)+e^(-)`
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