Give reasons of the following:
Why is sodium chloride added during electrolysis of fused anhydrous magnesium chloride?

The IUPAC name of the compound
CH₂ = CH $$-$$ CH(CH₃)₂

An unknown compound of carbon, hydrogen and oxygen contains 69.77% carbon and 11.63% hydrogen and has a molecular weight of 86. It does not reduce Fehling solution, but forms a bisulphite addition compound and gives a positive iodoform test. What are the possible structures?

The solution set of the system of equations $$X + Y = {{2\pi } \over 3},$$ $$cox\,x + cos\,y = {3 \over 2},$$ where x and y are real, is _____.