In the Chemistry optional subject for UPSC, there are several topics that require knowledge of inorganic chemistry. Inorganic chemistry is the study of the properties and behavior of inorganic compounds, which includes elements and compounds that do not contain carbon-hydrogen bonds. Here are some specific topics in the Chemistry optional subject that require knowledge of inorganic chemistry:

1. Periodic Table and Chemical Bonding:
- The periodic table is a fundamental tool in inorganic chemistry that organizes elements based on their properties.
- Understanding the periodic trends, such as atomic size, ionization energy, electron affinity, and electronegativity, is crucial for analyzing chemical bonding.
- Chemical bonding, including ionic, covalent, and metallic bonding, is a central concept in inorganic chemistry and is applicable in various topics.

2. Coordination Chemistry:
- Coordination compounds are complex substances in which a central metal atom or ion is surrounded by ligands.
- Knowledge of coordination chemistry is essential for understanding the structure, bonding, and properties of coordination compounds.
- Topics within coordination chemistry include nomenclature, isomerism, stability, and various bonding theories.

3. Chemical Thermodynamics and Chemical Kinetics:
- Inorganic reactions often involve thermodynamic and kinetic aspects.
- Thermodynamics deals with the energy changes in chemical reactions, including enthalpy, entropy, and free energy.
- Kinetics focuses on the speed of chemical reactions, including factors affecting reaction rates, rate laws, and reaction mechanisms.

4. Main Group Chemistry:
- Main group elements, such as alkali metals, alkaline earth metals, halogens, and noble gases, play significant roles in inorganic chemistry.
- Topics within main group chemistry include their properties, reactivity, compounds, and applications.

5. Analytical Chemistry:
- Inorganic chemistry is also crucial in analytical chemistry, which involves the identification and quantification of chemical species.
- Techniques such as spectrophotometry, atomic absorption spectroscopy, and voltammetry are commonly used to analyze inorganic compounds.

In summary, inorganic chemistry is an integral part of the Chemistry optional subject for UPSC. Topics such as the periodic table, chemical bonding, coordination chemistry, thermodynamics, kinetics, main group chemistry, and analytical chemistry rely heavily on knowledge of inorganic chemistry. Understanding these topics is essential for a comprehensive understanding of the subject and performing well in the examination.