Statement I: The standard reduction potential EAl3+/Al∘ is −1.66 V, which is highly negative, indicating that aluminium has a strong tendency to lose electrons and is highly electropositive. The standard reduction potential ETl3+/Tl∘ is +1.26 V, which is positive, indicating that thallium is less electropositive than aluminium. Thus, Statement I is true.
Statement II: Boron has a very small atomic size, resulting in a very high sum of its first three ionization enthalpies. This high energy requirement prevents boron from losing three electrons to form B3+ ions, so it forms only covalent compounds. In contrast, aluminium has a larger size and a significantly lower sum of its first three ionization enthalpies, allowing it to easily form Al3+ ions in its compounds. Thus, Statement II is true.
Both Statement I and Statement II are true.
Answer: Both Statement I and Statement II are true