Thermodynamics

If 100 mole of H₂O₂ decompose at 1 bar and 300 K, the work done (kJ) by one mole of O₂(g) as it expands against 1 bar pressure is : 2H₂O₂(l)    $\rightleftharpoons$    2H₂O(l) + O₂(g) (R = 8.3 J K ^$-$1 mol^$-$1)