Question

In case of oxygen family (Group $16$):
A.The tendency for catenation decreases markedly as we go down the group
B.Maximum coordination of oxygen is four due to lack of d-orbital but that of other elements is six due to presence of d-orbital.
C.The tendency to form multiple bonds with $C,N,O$ decreases as going down the group from $S$ to $Te$.
D.All of the above are correct statements

Answer 1

The most commonly observed catenation behaviour is shown by carbon, and the whole field of organic chemistry is based on it, in a way.
Presence of d-orbitals helps in bond formation as it has room for electrons of upcoming elements hence they can form bonds and have higher coordination number than those elements which don't have d-orbitals.

Complete step by step answer:
Catenation is a tendency which can be observed in an element, to bind with itself through covalent bonds in order to form chain or ring molecules. Example of an element which is most commonly observed in nature is catenation. As we go down the group the catenation tendency decreases, in the oxygen family catenation is shown by only oxygen and sulphur. And it is maximum in case of sulphur which is up to $10$ atoms. This is because as we go down the group the size of the atoms increases, so the bond strength decreases and the ability of the atoms to show catenation also decreases. So option A is correct.
Maximum coordination of oxygen is four because oxygen does not have vacant d-orbitals, so it cannot have more than four valence and thus has a limited coordination number. In other words it cannot bind with more than four other atoms at once, because of lack of empty d-orbitals. While in case of other elements, because they are bigger in size they already have the d-orbitals inside them, which makes it possible for them to have higher coordination. So option B is also correct.
In case of option C, in case of carbon, nitrogen and oxygen, the ability of their multiple bond formation decreases down the group, as the size of the elements increases the bond between them and $C,N,O$ decreases as their size is much smaller in comparison. So option C is also correct.
Since all of these statements given in the option are true, the correct option is D.

Note: Catenation is the tendency of an atom to form bonds with the same atoms. The Oxygen family has sulphur which has the highest catenation up to ten atoms.
-Maximum coordination of oxygen is four and others have more than that because oxygen is the first element in the group hence the smallest, so it doesn’t have presence of d-orbitals which could help in bond formation and have coordination number more than four, like in case of the other elements.