Strategy for Chemistry Optional for UPSC

Chemistry is one of the optional subjects that a candidate taking the UPSC civil service exam can opt for. It is a core science subject and so, there are not many takers for this subject. However, there have been candidates who have secured high marks in the chemistry optional papers and also bagged good ranks in the UPSC exam. In this article, you will read all about the chemistry optional for the IAS mains exam – strategy for both papers, syllabus, toppers, etc.

How many take Chemistry optional?

The number of candidates who opt for chemistry as their optional is not very high unlike subjects like pub ad or geography. But on an average, anywhere between 70 and 120 people take up this optional. In 2016, as per the latest available data, 124 candidates had taken chemistry out of which only 7 made it.

The following table shows the success rates of candidates with chemistry optional:

Year No. of candidates appeared No. of candidates cleared Success rate (%)
2016 124 7 5.6
2015 92 11 12
2014 98 7 7.1
2013 85 6 7.1
2012 104 11 10.6
2011 123 11 8.9
2010 107 7 6.5
2009 109 9 8.3
2008 124 7 5.6
2007 110 9 8.18
2006 89 5 5.6
2005 84 4 4.8
2004 109 0 0
2003 133 7 5.3
2002 75 2 2.6

Toppers with chemistry optional

There have been toppers with the chemistry optional in the UPSC exam. In fact, in 2002, the first ranker, Ankur Garg, had chemistry as one of his optionals. The next table gives the names of a few toppers with the chemistry optional.

Name Year Rank
Ankur Garg 2002 1
Pulkit Garg 2015 27
Charchit Gaur 2015 96
Rahul Gupta 2016 182
Deepesh Kedia 2017 221

Chemistry optional pros and cons

There are advantages and disadvantages in taking a core science subject like chemistry as the optional in the IAS mains. Some of the major points are discussed below.

Chemistry optional pros

Science subject

Chemistry is considered a scoring subject as it is a precise science unlike the humanities or social sciences. The concepts cannot be interpreted in multiple ways and nothing is subjective. This makes the marking more predictable.

Scoring subject

Chemistry is a scoring subject because there is ample scope for diagrams and equations. You also have numericals in this paper which when done correctly can fetch you maximum marks for the question. Additionally, with conceptual clarity, you can write good answers and get high marks. Many candidates have secured 300+ in this optional which is very rare in humanities optionals.

Static portions

Most of the syllabus is entirely static.

Less competition

Because of the less number of candidates who opt for this optional, the competition you will face with this optional is quite less.


There is a minor overlap with GS papers particularly in topics such as environment, climate change, new scientific technologies like nanotechnology, fibre optics, etc.

Chemistry optional cons

  • You should have a background in chemistry if you wish to take up this optional.
  • You should genuinely have an interest in reading chemistry otherwise it would be very difficult to complete the syllabus.
  • The syllabus will take at least 6 months to complete.
  • There is very little overlap with the general studies papers.
  • You have to write precise answers as it is a core science subject. You cannot beat about the bush in any answer and hope to get minimum marks.

Chemistry optional syllabus

Let us take a look at the syllabus for chemistry for the UPSC mains exam.

There are two optional papers in the UPSC exam pattern. Both the papers are for a total of 250 marks making the total optional marks to 500.

Download the Chemistry syllabus PDF.

Chemistry optional strategy

General tips for chemistry optional

  1. The most important step in your chemistry optional preparation is to be well-versed with the syllabus. Have a copy of the UPSC syllabus for chemistry optional ready by your side always.
  2. Before you start the detailed topic-wise preparation of this subject, you must be prepared with the basics first. For this, you can start with the XI and XII NCERT textbooks of chemistry. This is especially for those candidates who have had lost their touch with the subject.
  3. Go through the previous years’ UPSC question papers and understand what are the portions of the syllabus from where questions are asked repeatedly. It is advisable that you complete the entire syllabus, but, this exercise will help you know which portions can be given more importance.
  4. Make short notes and mnemonics to remember certain things like periodic table, etc.
  5. Regular revision is extremely important in a paper like chemistry. There are a lot of theories, concepts, equations, etc. to study.
  6. Numericals are tricky. In case you present the correct answer with sufficient background theory, you may get full marks for the question. But if the answer is incorrect, you may lose the entire marks.

In the next section, we discuss topic-wise preparation strategy for chemistry optional.

Chemistry paper I

  1. Atomic structure – this is a relatively easy topic. There are some basic concepts. You can refer to ‘Principles of Physical Chemistry’ by Puri, Sharma & Pathania for this section. Do go through the previous question papers for this section.
  2. Chemical bonding – this is the most important topic in this paper. For this section, you can read Physical Chemistry by KL Kapoor. Stick to the syllabus because this is a very vast topic which involves high level of mathematics (which is not at all relevant for UPSC). Some problematic topics in this section are molecular orbital theory and valence bond theory and their mathematical aspects. To tackle these, go through previous question papers and try to find out the answers from KL Kapoor, this would be sufficient.

Example question:

  • What is an orbital and how is it related to probability density? (5 marks, 2018)
  • Determine the geometry of [Ni(H2O)6]2+ (paramagnetic complex with two unpaired electrons) using valence bond theory. (5 marks, 2018)
  • Point out the main features of the Valence Bond and Molecular Orbital theories. For the H2 molecule, write down the wave function using: (10 marks, 2014)

(i) Valence Bond Theory

(ii) Molecular Orbital Theory

3. Solid state – this is an easy topic and KL Kapoor would be enough for it. You can also refer to the NCERTs for this section as it explains the concepts in a simple manner.

4. Gaseous State and Transport Phenomenon – this is also an easy chapter and the UPSC has always asked very basic questions from here. The most important source for this section is Puri, Sharma and Pathania. In this section, collision theory is very important and even numericals are asked from this.

5. Liquid State – you can easily do it from KL Kapoor.

6. Thermodynamics – for this section, you can refer to Puri, Sharma and Pathania. Again, only basic questions are asked.

Example question:

  • At constant pressure, the temperature of a fixed amount of hot tea in a cup decreases spontaneously to room temperature. What will be the sign of (I) ΔH and (II) ΔG of this process? Give reasons in support of your answer. (10 marks, 2018)

7. Phase Equilibria and Solutions – many candidates tend to ignore this section. That would be a mistake.

8. Electrochemistry – this is a very vast portion of the syllabus. You can refer to Puri, Sharma and Pathania or KL Kapoor for this section.

9. Chemical Kinetics – this section is generally easy. Sometimes, numericals are asked from activation energy topic. Any basic book will cover this section.

Example question:

  • What are the characteristics, essential for catalysis with specific reference to surface catalysis? (10 marks, 2018)
  • Define activation energy, Ea of a chemical reaction. A gas-phase reaction completes 25% in 30 min at 27oC and in 10 min at 37oC. Determine the Ea in SI unit. (15 marks, 2018)

10. Photochemistry – this is largely based on chemical kinetics section. Even though not mentioned explicitly in the syllabus, do read Grotthuss–Draper law and Einstein’s law. Questions have been asked from these topics.

11. Surface Phenomena and Catalysis – you should study the derivations of all the theories here. You can refer to either KL Kapoor or Puri, Sharma and Pathania.

The above sections dealt with physical chemistry. The following deals with inorganic chemistry.

12. Bio-inorganic Chemistry – you can refer to Inorganic Chemistry by James Huheey. This is a very important book for entire inorganic chemistry.

13. Coordination Compounds – Huheey is sufficient for this topic.

Example questions:

  • What is meant by EAN rule applied to complexes? Apply the concept of EAN rule on the following two complexes [Fe(CN)6]4- and [Fe(CN)6]3- and draw your conclusion about the validity of the rule. (10 marks, 2017)

14. Main Group Chemistry – for this section, NCERTs and Huheey are important.

15. General Chemistry of ‘f’ Block Elements – Huheey is sufficient for this topic.

Chemistry Paper II

Paper II deals with organic chemistry. This is a crucial section because with a little extra practice and conceptual clarity, you can score high marks.

  1. Delocalised Covalent Bonding – you can refer to Peter Sykes for Organic Chemistry.
  2. Reaction Mechanisms –  this is a very important chapter in organic chemistry. In fact, it is very important to understand this concept as many topics are related to this. Peter Sykes is a good reference book for this topic.

In rearrangements and named reactions, you must focus on why the reaction is happening. Understand every step of the reaction. This will help you answer questions on them. You must literally mug up the named reactions for the exam.

Example questions:

  • With suitable example, comment whether Fries Rearrangement proceeds intermolecularly or intramolecularly. Give evidence in favour of your answer. (5 marks, 2018)

3. Pericyclic Reactions – you can refer to Organic Chemistry by Clayden or Peter Sykes for this topic.

4. Polymers – questions are asked every year from this section. Do not leave any topic from here.

Example questions:

  • Give the synthetic schemes including reaction conditions for the preparation of the following polymers from their monomers: (15 marks, 2018)

(i) Nylon 66

(ii) Teflon

(iii) Terylene

  • Distinguish between RNA and DNA with regard to their nucleotide structures, location in the cells and functions. (10 marks, 2018)

5. Synthetic Uses of Reagents – this is a very easy and scoring section. Questions are asked every year mostly.

6. Photochemistry – you must practice questions for this section specifically. This is tricky as it deals with free radicals and they can react anytime with anything! But, practice should help you here, and also the UPSC does not ask very vague questions from here. Photochemistry and Pericyclic Reactions by Jagdamba Singh is good for this.

7. Spectroscopy – refer to previous question papers to understand the type of questions asked from here. The book recommended for this is Spectroscopy of Organic Compounds by PS Kalsi. Here, some question types that are repeated are to calculate the lambda max, mass spectra, NMR (structure and signals), and IR spectra reasoning.

Chemistry optional books

  • Principles of Physical Chemistry by Puri, Sharma & Pathania
  • Physical Chemistry by KL Kapoor
  • Inorganic Chemistry by James Huheey
  • Organic Chemistry by Peter Sykes
  • Organic Chemistry by Clayden
  • Photochemistry and Pericyclic Reactions by Jagdamba Singh
  • An Introduction to Electrochemistry by Samuel Glasstone
  • Concise Inorganic Chemistry by J.D. Lee
  • Spectroscopy of Organic Compounds by PS Kalsi
  • NCERT textbooks of classes XI and XII for Chemistry

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