Question

How to find valency of elements of Block-D in periodic table?

Answer 1

Firstly, it depends on what you count as "valence electrons". If you say that, for all the d-block metals, the ns and (n-1)d electrons count as "valence electrons", then the answer is to just look at the group number. However, that obviously doesn't work for Zn, which effectively only has 2 valence electrons. That's really an extreme case though. It is sometimes said that the d electrons transition from being valence electrons in the early d-block (hence Sc only forms Sc3+ScX3+), to being core electrons in the late d-block (hence Zn only forms Zn2+ZnX2+). 

Answer 2

It start from 3and in middle 0 goes to2