[Hrushikesh]

∆G=∆H-T∆S
     =(∆E+∆PV)-T(q/T)
     =q+w+P∆V+V∆P-q
     =-P∆V+P∆V+V∆P
     =V∆P
!!!!! This means that at constant P and T ∆G is always zero.
Please tell me is this correct or not.
If not tell me where.

[mjc123]

The equations ΔE = q + w and ΔS = q/T apply only to a system that undergoes no chemical changes. Then it is no surprise that at constant P and T ΔG = 0, because G is a state function. If there is a reaction, you have to consider the energy and entropy changes between reactants and products.