${\mathrm{E}}_{{\mathrm{Al}}^{3+}/\mathrm{Al}}^{\mathrm{o}}=1.66 \mathrm{V}$ and ${\mathrm{E}}_{{\mathrm{Tl}}^{3+}/\mathrm{Tl}}^{\mathrm{o}}=1.26 \mathrm{V}$. Then which of the following statements is correct ?

a) Aluminium has high tendency to form ${\mathrm{Al}}^{3+}$ ions in aqueous solution.

b) ${\mathrm{Tl}}^{3+}$ is unstable in aqueous solution

c) ${\mathrm{Tl}}^{3+}$ is a powerful oxidizing agent

d) Al is a powerful reducing agent

${\mathrm{Al}}^{3+}$(aq) ions are produced by two half-cell reactions at standard electrode potentials, whereas ${\mathrm{Tl}}^{3+}$ is not only unstable in solution but also a strong oxidizer. ${\mathrm{Tl}}^{+}$ is therefore more soluble than ${\mathrm{Tl}}^{3+}$. Aluminium is more electropositive than thallium because it can easily produce +3 ions.

Therefore, the correct option is (D).