Standard electrode potential values 
and that of 
is +1.26 V. Predict about the formation of M3+ ion in solution and compare the electropositive character of the two metals.
Standard electrode potential values for two half-cell reactions indicate that aluminium has a high tendency to form Al3+ (aq) ions, while Tl3+ is not only unstable in solution but is also a powerful oxidising agent. Thus Tl+ is more stable in solution than Tl3+. Since aluminium being able to form +3 ions easily, therefore it is more electropositive than thallium.
