Question

$Be$ and $Al$ have following resemblance due to diagonal relationship:

• A. Have nearly equal electronegativity
• B. Form amphoteric oxides
• C. Have strong tendency to form complexes, $Be{F}_4^{-2},Al{F}_6^{-3}$
• D. Both form dimeric halides

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A Have nearly equal electronegativity
B Form amphoteric oxides
C Have strong tendency to form complexes, $Be{F}_4^{-2},Al{F}_6^{-3}$
D Both form dimeric halides

Electronegativities:

$Be-1.57$
$Al-1.61$

Both $BeO$ and $A{l}_2{O}_3$ are amphoteric - as in they react with both acids as well as bases.
$BeO+2HCl⟶BeC{l}_2+H_{2}O$

$BeO+2NaOH+H_{2}O⟶N{a}_{2}Be(OH{)}_4$

Likewise, $A{l}_2{O}_3$ is amphoteric:

$A{l}_2{O}_3+6HCl⟶2AlC{l}_3+3H_{2}O$

$A{l}_2{O}_3+2NaOH+3H_{2}O⟶2NaAl(OH{)}_4$

Also, they both form dimeric halides; Further, both can form complexes:
$Be{F}_4^{-2},Al{F}_6^{-3}$