Which of the following elements forms stable di-nuclear ions?

Options

A. Zn
B. Cd
C. Hg
D. Fe

Answer

C

Explanation

Hg (I) compounds contain mercurous ions `(Hg-Hg)^(2+) and not Hg^(+).` The two Hg atoms are bonded together using 6s-orbital. The only other metals which forms di nuclear ions are `(Zn-Zn)^(2+) and (Cd-Cd)^(2+).` But, these ions are unstable and have been only detected in melts of `Zn//ZnCl_(2) and Cd//Cd Cl_(2)` spectroscopically.