Question

Which of the following does not form ${\mathrm{M}}^{3+}$ more easily among group 13 elements?

• A. $\mathrm{B}$
• B. $\mathrm{Al}$
• C. $\mathrm{Ga}$
• D. $\mathrm{In}$

Answer 1

The correct option is A

$\mathrm{B}$

Explanation for correct option:

A. $\mathrm{B}$

Boron:

• Out of group -13 elements, Boron will not form ${\mathrm{M}}^{3+}$ easily due to many reasons such as:

1. The size of Boron is small as the atomic size increases down the group.
2. Boron does not form ${\mathrm{B}}^{3+}$ion due to its small size and high ionization energy.
3. The sum of its first three ionization enthalpies is very large. This restricts it to form $+3$ ion.

• Thus, boron does not form ${\mathrm{M}}^{3+}$easily due to its small size and high ionization energies.

Explanation for incorrect options:

The other elements of group-13 such as Aluminium$\left(\mathrm{Al}\right)$ , Gallium$\left(\mathrm{Ga}\right)$, and Indium$\left(\mathrm{In}\right)$ forms ${\mathrm{M}}^{3+}$ easily due to their large size and low ionization energy as compared to boron. Thus, options B, C, and D are incorrect.

Hence, the correct option is A i.e. Boron$\left(\mathrm{B}\right)$ .