Question

How to tell whether an element is paramagnetic or diamagnetic?

Answer 1

If it has some unpaired electrons, then it would be PARAMAGNETIC whereas if it has all paired electrons, then it would be DIAMAGNETIC.

Answer 2

First to write electronic configuration.
Then Draw the valence orbitals
After that Look for unpaired electrons.
If one or more electrons unpaired then its paraamagnetic , if  all electrons are paired then its diamagnetic.