Read the given passage and answer the questions number 1 to 5 that follow :
Originally the name transition metals was derived from the fact that their chemical properties were transitional between those of s and p-block elements. Now according to IUPAC, transition metals are defined as metals which have incomplete d-subshell either in the neutral atom or in their ions. Zinc, cadmium and mercury of Group 12 have full du configuration in their ground state as well as their common oxidation states and hence, are not regarded as transition metals. However, being the end members of the 3d, 4d and 5d transition series, respectively their chemistry is studied along with the chemistry of transition metals.
The presence of partly filled d or f-orbitals in their atoms makes transition elements different from that of the non-transition elements. Hence, transition elements and their compounds are studied separately. However, the usual theory of valence as applicable to the non-transition elements can be applied successfully to the transition elements also.
What is the original definition of transition metals ?

Explanation

The original interpretation of the words transition metals is that there is a transition (change) in the properties of the elements when we move from s-block elements to p-block elements.