Give reasons for the following - pertaining to Hall Herault's process.
A layer of powdered coke sprinkled over the lectrolytic mixture, protects the carbon electrodes.

Why is powdered coke sprinkled over the electrolytic mixture ?

Give reasons for the following - pertaining to Hall Herault's process. The fusion temperature of the electrolyte has be lowered before conducting the electrolytic reduction.

Give reasons for the following - pertaining to Hall Herault's process. The constituents of the electrolyte in addition to one part of fused alumina contains three parts of crylite and one part of fluorspar.

Give reasons for the following - pertaining to Hall Herault's process. It is preferred to use a number of graphite electrodes as anode, instead of a single graphite electrode.

Answer the following questions with respect to the electrolytic process in the extraction of aluminum : Explain why powdered coke is sprinkled over the electrolytic mixture.

Answer the following questions based on the ectraction of aluminium from alumina by Hall - Heroult's Process. Why is powdered coke sprinked on top of the electrolyte.

Give reasons for the following: 'Sodium carbonate is prepared by Solvay process but the same process is not extended to the manufacture of potassium carbonate'.

Give reasons for the following : (a) When 2g of benzoic acid is dissolved in 25 g of benzene, the experimentally determined molar mass is always greater than the true value. (b) Mixture of ethanol and acetone shows positive deviation from Raoult's Law. (c) The preservation of fruits by adding concentrated sugar solution protects against bacterial action.

In an experiment to estimate the size of a molecule of oleic acid 1 mL of oleic acid is dissolved in 19 mL of alcohol. Then 1 mL of this solution is diluted to 20 mL by adding alcohol. Now, 1 drop of this diluted solution is placed on water in a shallow trough. The solution spreads over the surface of water forming one molecule thick layer. Now, lycopodium powder is sprinkled evenly over the film and its diameter is measured. Knowing the volume of the drop and area of the film we can calculate the thickness of the film which will give us the size of oleic acid molecule. Read the passage carefully and answer the following questions (a) Why do we dissolve oleic acid in alcohol ? (b) What is the role of lycopodium powder? (c) What would be the volume of oleic acid in each mL of solution prepared? (d) How will you calculate the volume of n drops of this solution of oleic acid ? (e) What will be the volume of oleic acid in one drop of this solution ?

Give one word or phrase for the following: Process which protects iron from rusting, it is coated with a thin layer of zinc.