Question

# $Zn,Cd$ and $Hg$are not regarded as transition elements. Give reason.

Zinc, cadmium, and mercury are group $12$ elements in the periodic table. They are placed in d-block elements as their valence electron enters into the d-subshell.
Additional Information:- $Zn,Cd$ and $Hg$ have low values of enthalpies of atomization. They all are soft metals as their all electrons are paired and metallic bonds are not strong enough. Zinc and cadmium shows $+ 2$ oxidation state whereas mercury shows $+ 1, + 2$ oxidation states. Zinc is diamagnetic in nature. All three elements occur naturally. They are widely used in electric and electronic applications as well as in various alloys. Zinc and cadmium show similar properties as they are solid metals at standard conditions. Mercury is the only metal that is a liquid at room temperature. Cadmium and mercury both are highly toxic but zinc is very important in the biochemistry of living organisms.