Presence of unpaired electrons makes a species paramagnetic. Each unpaired electron has a magnetic moment associated with its spin angular momentum and orbital angular momentum. For the compounds of the first series of transition metals, the contribution of the orbital angular momentum is effectively quenched and hence is considerably important. For these, the magnetic moment is determined by the number of unpaired electrons and is calculated by using the spin-only formula, i.e., `mu = sqrt(n(n+2))` where n=number of unpaired electrons and `mu`=magnetic momentin (in Bohr magneton, B.M.). If n=1, then `mu = 1.73 B.M`.
Which one of the following transition metal ions is paramagnetic?

Options

A. `3d^7`
B. `Zn^(2+)`
C. `Cu^(2+)`
D. `Au^(+)`

Answer

C

Explanation

`Cu^(2+) ` has `d^9` configuaration with one unpaired electron and is paramagnetic whereas ` Ag^(+) , Zn^(2+) and Au^(+)` has ` d^(10)` configuration and are diamagnetic