Question

Number of correct statement among the following is
(A) The electron affinity of $Si$ is greater than that of $C$
(B) $BeO$ is amphoteric while $B_2{O}_3$ is acidic.
(C) The ionization energy of $Ga$ is less than that of $Al$.
(D) The ionization energy of elements of $Cu$ - group is less than that of the respective elements of $Zn$ - group.

Answer 1

(A) The electron affinity of $Si$ is greater than that of $C$, because $Si$ has vacant $3d$ orbitals where it can accomodate electrons. On the other hand $C$ is small in size and thus, interelectronic repulsion is more in $C$.

(B) $Be$ has a digonal relationship with $Al$. Hence $BeO$ is amphoteric like aluminium oxide. Boric oxide ($B_2{O}_3$) is acidic since as we move from left to right, the acidic nature of the oxides increases.

(C) Ionisation energy decreases down the group. However, due to poor shielding of $3d$ electrons, d block contraction happens and ionization energy of $Ga$ is greater than that of $Al$.

(D) Ionization energy of the $Zn$ group is greater than that of $Cu$ -group because of the stable elctronic configuration of $Zn$ having completely filled valence shell.