Question

Which one is not paramagnetic among the following? [at. no. of $Be = 4, N e = 10$ , $A s= 33,Cl= 17$]

• A. $Cl^-$
• B. Be
• C. $Ne^{2+}$
• D. $As^+$

Answer 1

Answer: (A)

$Cl^-$

Answer 2

Paramagnetic character is based upon presence of unpaired electron
$_{17}Cl^- = 1s^2 ,2s^2 2p^6,3s^2 3p_x^2 3p_y^2 3p_z^2$
In $Cl^-$ no unpaired electron, so diamagnetic.
$_ 4 Be = 1s^2 ,2s^1 2p_x^1$
$_{10} Ne^{2+} = 1s^2 , 2s^2 2p_x^2 2p_y^1 2p_z^1$
$_{33}As^+ = 1s^2 ,2s^2 2p^6 , 3s^2 3p^6 3d^{10} ,4s^2 4p_x^1 4p_y^1 4p_z^0$
While all others have unpaired electron, so paramagnetic in nature.