Identify the incorrect statements among the following 

Fluoroethane reacts with  $Znanddil.HCl$ and gives ethane as major product

n-octane on heating to  ${73}^{\circ }C$ at 10 to 20 atm in presence of  $V_2{O}_5$  gives meta-xylene as one of the product

Sodium salts of carboxylic acids on electrolysis give $C{O}_2$ gas at cathode and hydrocarbon at anode

The minimum carbon atoms in an alkane required to show positional isomerism is 6.