In which direction does the reaction proceed when the volume is increased in case of delta n positive reaction?

Why?

If you increase the volume , the concentration = mol/V , it will reduce and hence it will move backward .

The fundamental effect of a change in volume is to simultaneously change the partial pressures (and molar concentrations) of all reactants and products by the same relative amount. If the volume of the gas is reduced, the concentrations of all reactants and products are simultaneously increased, which corresponds with an increase in the total concentration of species in the gas. Using Le Châtelier's Principle, the system should react in a way to oppose this stress; that is, the system should react to reduce the total concentrations.