IFoS – Forestry optional

My score – 254/400
There are two papers of 200 marks each. It is possible to score unto 65% in this optional (as per this year marking)
Book list and resources


  •  I went through entire syllabus before prelims once. This helped me in saving precious time between Prelims and Mains as CSE mains was also lined up after IFoS’s
  • I made few shorts notes for revision especially
  • I solved the questions that are given at the end of each chapter in the book. Wikipedia and internet research helped
  • Draw as many diagram as possible – colour them if you can
  • Don’t take it lightly because it has same marks as other optional as well as more marks than GK

IFoS – Physics optional

My score – 278/400
I joined DIAS for Physics classes and their test series. More than anything else, the motivation by Vajpayee Sir played an important role in me getting good marks in Physics.
To do
  • Solve all DIAS tutorials properly in UPSC like notebook – Gives you a feel of space, presentation etc
  • Don’t leave any fringe topics especially those which are not in CSE syllabus- Lagrangian and Hamiltonian mechanics, saha’s ionization, cornu’s spiral etc
    • There’ll be invariably 1-2 questions from these and if you have prepared them well, they can give you an edge.
  • Prepare revision notes (summary sheets – 3-4 pages for each units)
    • Cant emphasize the importance of this. If you don’t have these, you’ll be overwhelmed just before the exam by the sheer size of the notes.
  • For those who join DIAS
    • Attend all classes
    • Solve tutorials as per schedule
    • Give all test on time
Book list
  • Mechanics
    • JCUpadhyay
  • Optics
    • Ghatak
  • Electricity and magentism
    • Griffith and SP
  • Thermo
    • Garg, bansal, ghosh
  • Resnick and Eisberg
  • Quantum
    • HCV
  • Atomic and molecular
    • Rajkumar and ban well
  • Nuclear and Particle
    • SBPatel
  • Solid state and digital electronics
    • Puri and babbar
Please remember that this is a test of your perseverance and balanced approach and not of your smartness.

IFoS – Optional

As per current pattern one has to choose two optional for IFoS. Each of them have two paper of 200 marks each. This means both optionals together form a total of 800/1700 in your final score

From the notification, the options to choose optional are –

  • (i) Agriculture
  • (ii.) Agricultural Engineering
  • (iii)  Animal Husbandry & Veterinary Science
  • (iv)  Botany
  • (v)  Chemistry
  • (vi)  Chemical Engineering
  • (vii)  Civil Engineering
  • (viii) Forestry
  • (ix)  Geology
  • (x)  Mathematics
  • (xi)  Mechanical Engineering
  • (xii)  Physics
  • (xiii) Statistics
  • (xiv) Zoology
Provided that the candidates will not be allowed to offer the following combination of subjects :
  1. (a)  Agriculture and Agricultural Engg.
  2. (b)  Agriculture and Animal Husbandry & Veterinary Science.
  3. (c)  Agriculture and ·Forestry.
  4. (d)  Chemistry and Chemical Engg.
  5. (e)  Mathematics and Statistics.
  6. (f)  Of the Engineering subjects viz. Agricultural Engineering, Chemical Engineering, Civil Engineering and Mechanical Engineering- not more than one subject;

My 2 cents – choose your optional wisely. As far as possible – Forestry should be one of the optional. This is because if you prepare it beforehand, it will help you in prelims (environment portion), CSE mains (allelopathy type question in GS3 – 2016 paper), IFoS interview (they are definitely going to ask something from forestry even if you dont have it as an optional)