
⭐ Elements in which the last electron enters any one of the five d-oribitals of their respective penultimate shells are called as <u>d-block</u><u> </u><u>elem</u><u>ents</u> .
⭐ But the last electron of Zn , Cd , Hg and Cn enters in the s-oribital of their respective ultimate shells rather than the d-oribitals of their respective penultimate shells . Therefore, these elements cannot be regarded as d-block elements .
☃️ But properties of these elements resemble to the d-block elements rather than s-block elements .
☃️ Therefore, to make the study of periodic classification of elements more rational, they are studied along with d-block elements .
✍️ Thus <u>on the basis of properties</u> all transition elements are d- block elements, but <u>on the basis of electronic configuration</u> all d -block elements are not transition elements .
Answer:- 
Explanations:- Let's say the first molecule is A and the second molecule is B and the product molecule is C.
From given information, 2 molecules of A react with 3 molecules of B to produce 5 molecules of C.
We write the reactants on left side and the product on right side and there is an arrow between them from reactants towards the products.
So, the reaction could be represented as:

Can u write it more specifically? so that I can answer