Define catenation. How it vary it nitrogen family. 

Define oxidation state. How does it vary in the groups ?

Define electron gain enthalpy. How it varies in a group and in a period ? Why is the electron gain enthalpy of O or F is less negative than that of succeeding element in the group ?

Which of the following group elements are nitrogen family ?

Discuss the general characteristics of nitrogen family and justify their position in the same group.

What is valency of an element? How does it vary with respect to hydrogen in the third period.

Define and explain the order of a reaction. How is it obtained exprimentally ?

Define Gibbs energy. How is it related to enthalpy and entropy?

Mention the oxidation numbers of the elements of nitrogen family in their compounds.Write suitable examples.