Theory Snapshot

Science is the story of questions asked and the people who answered them. From the falling apple that sparked Newton’s gravity to the mysterious compass that guided Einstein toward relativity, every law, unit and symbol we use today was once someone’s lifetime obsession. Railway exams expect you to recall the “who gave what” linkage—mainly physicists, chemists and biologists whose discoveries changed transport, health, energy and communication.

The examiner’s favourite 30-odd names can be grouped into (a) Laws & Units—Newton, Joule, Ohm, Watt, Roentgen, Curie; (b) Evolution & Genetics—Darwin, Lamarck, Mendel, Watson-Crick; (c) Micro-world & Disease—Pasteur, Koch, Fleming, Jenner; (d) Modern Physics—Planck, Einstein, Rutherford, Bohr; (e) Space & Satellite—Kepler, Galileo, Kalam, S. Chandrasekhar. Link each scientist to one keyword (law, particle, theory, vaccine, satellite) and you are 90 % done. The remaining 10 % is remembering nationality, year and Nobel Prize tags.

Practice MCQs

1. Who gave the three laws of planetary motion?

• A. Galileo Galilei
• B. Johannes Kepler
• C. Tycho Brahe
• D. Isaac Newton
  AnswerCorrect: Option B. Explanation: Kepler’s three laws (1609, 1619) describe elliptical orbits, equal-area sweep & harmonic relation.

2. The unit of electric resistance is named after which scientist?

• A. Alessandro Volta
• B. André-Marie Ampère
• C. Georg Simon Ohm
• D. Michael Faraday
  AnswerCorrect: Option C. Ohm formulated V = IR in 1827; SI unit ohm (Ω).

3. “Principia Mathematica” was written by

• A. Kepler
• B. Newton
• C. Einstein
• D. Galileo
  AnswerCorrect: Option B. Newton’s 1687 work contains laws of motion & universal gravitation.

4. Penicillin was discovered by

• A. Robert Koch
• B. Louis Pasteur
• C. Alexander Fleming
• D. Joseph Lister
  AnswerCorrect: Option C. Fleming noticed mould killing bacteria in 1928.

5. The small-pox vaccine was first developed by

• A. Edward Jenner
• B. Jonas Salk
• C. Albert Sabin
• D. Ronald Ross
  AnswerCorrect: Option A. Jenner used cowpox in 1796.

6. “Origin of Species” was published in

• A. 1759
• B. 1809
• C. 1859
• D. 1909
  AnswerCorrect: Option C. Charles Darwin’s book introduced natural selection.

7. The atomic nucleus was discovered by

• A. J. J. Thomson
• B. Ernest Rutherford
• C. Niels Bohr
• D. James Chadwick
  AnswerCorrect: Option B. Gold-foil experiment, 1911.

8. The neutron was discovered by

• A. Rutherford
• B. Chadwick
• C. Fermi
• D. Pauli
  AnswerCorrect: Option B. Chadwick, 1932; Nobel 1935.

9. Who explained photoelectric effect using quantum concept?

• A. Planck
• B. Bohr
• C. Einstein
• D. Heisenberg
  AnswerCorrect: Option C. Einstein, 1905 paper; Nobel 1921.

10. The triple-helix model of DNA was wrongly proposed by

• A. Watson & Crick
• B. Linus Pauling
• C. Rosalind Franklin
• D. Erwin Chargaff
  AnswerCorrect: Option B. Pauling’s 1952 model was corrected by Watson-Crick double helix in 1953.

11. “One gene-one enzyme” hypothesis was given by

• A. Beadle & Tatum
• B. Jacob & Monod
• C. Hershey & Chase
• D. Avery & McLeod
  AnswerCorrect: Option A. Neurospora experiments, 1941.

12. The law of inheritance independently rediscovered by

• A. Hugo de Vries, Correns & Tschermak
• B. Lamarck, Darwin, Wallace
• C. Haeckel, Weismann, Mendel
• D. Morgan, Sturtevant, Bridges
  AnswerCorrect: Option A. 1900 re-discovery of Mendel’s 1866 paper.

13. The term “radioactivity” was coined by

• A. Henri Becquerel
• B. Pierre Curie
• C. Marie Curie
• D. Ernest Rutherford
  AnswerCorrect: Option C. Marie Curie, 1898.

14. Which Indian physicist is known for “Boson”?

• A. C. V. Raman
• B. Meghnad Saha
• C. Satyendra Nath Bose
• D. Homi Bhabha
  AnswerCorrect: Option C. Bose-Einstein statistics, 1924.

15. The missile-man of India is

• A. Vikram Sarabhai
• B. A. P. J. Abdul Kalam
• C. R. A. Mashelkar
• D. K. Radhakrishnan
  AnswerCorrect: Option B. Kalam led SLV-3, Agni, Prithvi projects.

16. The unit of activity of radioactive substance is

• A. Gray
• B. Sievert
• C. Becquerel
• D. Curie
  AnswerCorrect: Option C. 1 Bq = 1 disintegration/s; SI unit.

17. Who gave the first accurate measurement of speed of light?

• A. Roemer
• B. Fizeau
• C. Foucault
• D. Michelson
  AnswerCorrect: Option A. Ole Rømer, 1676, using Jupiter’s moon Io.

18. “Cosmic rays” coined & studied extensively by

• A. Robert Millikan
• B. Victor Hess
• C. C. T. R. Wilson
• D. Karl Jansky
  AnswerCorrect: Option B. Hess, 1912 balloon flight; Nobel 1936.

19. The principle of rocket motion is based on

• A. Newton’s 1st law
• B. Newton’s 2nd law
• C. Newton’s 3rd law
• D. Archimedes principle
  AnswerCorrect: Option C. Action-reaction pair ejects exhaust.

20. Which scientist introduced the concept of “isotopes”?

• A. Soddy
• B. Aston
• C. Moseley
• D. Urey
  AnswerCorrect: Option A. Frederick Soddy, 1913.

21. “Principles of Geology” was written by

• A. Charles Lyell
• B. Alfred Wegener
• C. Arthur Holmes
• D. James Hutton
  AnswerCorrect: Option A. Lyell, 1830; influenced Darwin.

22. The first artificial transmutation of an element was done by

• A. Rutherford
• B. Irene Joliot-Curie
• C. Otto Hahn
• D. Ernest Lawrence
  AnswerCorrect: Option A. Rutherford, 1919; nitrogen → oxygen + proton.

23. “One gene-one polypeptide” revision was necessitated because of discovery of

• A. Exons
• B. Introns
• C. Split genes
• D. All of the above
  AnswerCorrect: Option D. Eukaryotic genes are discontinuous; hence polypeptide, not enzyme.

24. Which duo shared the 2020 Chemistry Nobel for CRISPR-Cas9?

• A. Doudna & Charpentier
• B. Zhang & Church
• C. Banerjee & Mukherjee
• D. Sharp & Roberts
  AnswerCorrect: Option A. Emmanuelle Charpentier & Jennifer Doudna.

25. The Chandrasekhar limit (1.4 M☉) relates to

• A. Maximum mass of white dwarf
• B. Minimum mass of neutron star
• C. Mass of black hole
• D. Mass of brown dwarf
  AnswerCorrect: Option A. Subrahmanyan Chandrasekhar, 1930; Nobel 1983.

Quick-fire Shortcuts

1. “NO E=mc² without PEM” – Planck (P), Einstein (E), Millikan (M) → Quantum & Photoelectric.
2. “Rutherford = Nucleus, Chadwick = Neutron, Bohr = Orbits” – 1-2-3 in order.
3. “Medals on the Chest” – Mendel, Darwin, Pasteur, Koch, Fleming → Disease & Evolution.
4. “Indian Nobel trio” – Raman (Physics), Chandrasekhar (Physics), Khorana (Medicine).
5. Unit = Scientist – °C (Celsius), J (Joule), W (Watt), N (Newton), Ω (Ohm), Bq (Becquerel).
6. Year shortcut – 1687 Principia, 1859 Origin, 1905 Miracle, 1911 Nucleus, 1953 DNA.
7. Railway GK favourite – Kalam → SLV-3, Agni, Prithvi; Vikram Sarabhai → ISRO founder.

Tip: Make a 5×6 table (Scientists vs. Discovery, Unit, Year, Nobel, Country) and glance daily; 70 % questions will fall within these 30 cells.