Yes, questions from coordination compounds and complex ions are commonly included in the chemistry section of the JEE Main exam. Here's a detailed explanation:

Coordination Compounds:
- Coordination compounds are an important topic in chemistry that deals with the formation, structure, and properties of complex compounds.
- These compounds consist of a central metal ion or atom surrounded by ligands, which are molecules or ions that donate electrons to the metal ion.
- Questions related to coordination compounds in the JEE Main exam often focus on topics such as nomenclature, isomerism, bonding, stability, and reactions of these compounds.
- Students are expected to understand the concept of coordination number, oxidation state, and coordination geometry of metal ions in these compounds.
- Common types of questions include identification of ligands, coordination numbers, and formulas of coordination compounds, as well as predicting the stability and reactivity of these compounds based on their structures.

Complex Ions:
- Complex ions are charged species formed by a central metal ion or atom surrounded by ligands.
- These ions can be positively charged (cations) or negatively charged (anions), depending on the overall charge of the complex.
- Questions on complex ions in the JEE Main exam often involve determining the coordination number, oxidation state, and electronic configuration of the central metal ion.
- Students should also be familiar with the structure, stability, and reactions of various complex ions.
- Common types of questions include identifying the ligands, coordination numbers, and charges of complex ions, as well as predicting the formation of complex ions in different chemical reactions.

Why are they important?
- Coordination compounds and complex ions are important in various areas of chemistry, including catalysis, bioinorganic chemistry, and materials science.
- Understanding these topics is crucial for students pursuing higher studies in chemistry or related fields.
- Mastery of coordination compounds and complex ions can also help students in solving problems related to chemical equilibrium, redox reactions, and coordination chemistry.

In conclusion, questions from coordination compounds and complex ions are frequently asked in the chemistry section of the JEE Main exam. Students should be well-prepared in these topics in order to perform well in the exam.