The standard reduction potential for several half-cells at 298K are given. Al3+ = -1.66v, Fe2+ = -0.44v, Sn2+ = -0.14v, Cu2+ = +0.34v, I2 = +0.54, Fe3+ = +0.77, Br2 = +1.07, Cl2 = +1.36, Mn3+ = +1.49. Which species is the most powerful oxidising agent?