Question

Which of the following pairs has almost same radii ?

• A. $Al,Ga$
• B. $Be,Mg$
• C. $Mg,Al$
• D. $B,Be$

Answer 1

Answer: (A)

$Al,Ga$

$Al$ electronic configuration is $\left[Ne\right]3s^{2}3p^1$

$Ga$ electronic configuration is $\left[Ar\right]4s^{2}3d^{10}4p^1$

The lectronic configuration of gallium shows that it contains 10 electrons in d -orbitals which do not screen the nucleus effectively because of the large size of d-orbitals, consequently the electrons are attracted by a greater force towards the nucleus, hence the atomic radius gallium decreases or gallium has almost same radii as that of alluminiu.

Hence option A is crrect.