Q20. Who discovered the principle of buoyancy?
[RRB NTPC – 2016]
(A) Archimedes
(B) Blaise Pascal
(C) Isaac Newton
(D) Galileo Galilei
Answer: (A) Archimedes
Explanation: Archimedes’ principle states that a body in a fluid experiences an upward buoyant force equal to the weight of the displaced fluid. This idea explains floating ships, submerged objects and the operation of hydrometers.
Q19. Who is credited in this examination with the discovery of carbon nanotubes?
[RPSC Assistant Engineer – 2016]
(A) Arthur Compton
(B) Abdus Salam
(C) Sumio Iijima
(D) Kip Thorne
Answer: (C) Sumio Iijima
Explanation: Sumio Iijima reported detailed observations of multiwalled carbon nanotubes in 1991, helping launch intensive research on these cylindrical carbon structures. Their mechanical strength, electrical characteristics and high aspect ratios support research into advanced materials and devices.
Q18. Alexander Fleming discovered which of the following?
[MPPSC State Services – 2016]
(A) Penicillin
(B) X-rays
(C) Streptomycin
(D) Telephone
Answer: (A) Penicillin
Explanation: Alexander Fleming discovered the antibacterial effect of penicillin in 1928. X-rays were discovered by Wilhelm Röntgen; streptomycin emerged from research by Albert Schatz and colleagues; the telephone is associated with Alexander Graham Bell.
Q17. Who discovered the antibiotic-producing fungus of the genus Penicillium?
[UPSC NDA – 2015]
(A) Louis Pasteur
(B) Sir Alexander Fleming
(C) Stanley Prusiner
(D) Robert Hooke
Answer: (B) Sir Alexander Fleming
Explanation: Fleming observed a Penicillium mould producing a substance that inhibited bacteria. He named the substance penicillin, which subsequently became a clinically important antibiotic following further research and manufacturing advances by other scientists.
Q16. Alexander Fleming discovered which of the following?
[MPPSC State Services – 2015]
(A) Penicillin
(B) X-rays
(C) Streptomycin
(D) Telephone
Answer: (A) Penicillin
Explanation: Penicillin was discovered by Alexander Fleming in 1928 during bacterial-culture experiments. Röntgen discovered X-rays, while Alexander Graham Bell is linked with the telephone. Streptomycin was discovered later by a research group involving Albert Schatz.
Q15. Who showed through scientific experiments that plants respond to stimuli and display life processes?
[MPPSC State Services – 2015]
(A) Robert Koch
(B) Jagadish Chandra Bose
(C) Benjamin Franklin
(D) Louis Pasteur
Answer: (B) Jagadish Chandra Bose
Explanation: Jagadish Chandra Bose conducted pioneering experiments on electrical and mechanical responses in plants. His crescograph magnified tiny growth movements, demonstrating that plant responses could be measured precisely, even though plant life was already known long before his work.
Q14. Who invented the xerographic process?
[RPSC College Librarian – 2014]
(A) Chester Carlson
(B) Benjamin Dancer
(C) Charles Babbage
(D) Paul Otlet
Answer: (A) Chester Carlson
Explanation: Chester Carlson invented electrophotography, later called xerography, in 1938. The technique uses electrostatic charges and light-sensitive materials to create images with toner. It became the basis of modern office photocopying and many laser printers.
Q13. Consider these scientist–theory pairs:
1. Continental drift — Edwin Hubble;
2. Expansion of the universe — Alfred Wegener;
3. Photoelectric effect — Albert Einstein.
Which pair is correctly matched?
[UPSC CSE Prelims – 2008]
(A) 2 and 3 only
(B) 3 only
(C) 2 only
(D) 1 only
Answer: (B) 3 only
Explanation: Alfred Wegener proposed continental drift, whereas Edwin Hubble contributed observations supporting an expanding universe; the first two pairings are reversed. Albert Einstein explained the photoelectric effect using light quanta, so only the third pair is correctly matched.
Q12. Which scientist shared a Nobel Prize in Physics with his son?
[UPSC CSE Prelims – 2008]
(A) Max Planck
(B) Albert Einstein
(C) William Henry Bragg
(D) Enrico Fermi
Answer: (C) William Henry Bragg
Explanation: William Henry Bragg and his son William Lawrence Bragg jointly received the 1915 Nobel Prize in Physics for their analysis of crystal structures using X-rays. Their work established X-ray crystallography as an important scientific method.
Q11. Which set of associations is correctly matched:
1. Francis Collins — human genome mapping;
2. Sergey Brin — Google;
3. Jimmy Wales — Wikipedia?
[UPSC CSE Prelims – 2008]
(A) 1 and 2 only
(B) 2 and 3 only
(C) 3 only
(D) 1, 2 and 3
Answer: (D) 1, 2 and 3
Explanation: Francis Collins directed the public Human Genome Project during a major phase of its work. Sergey Brin co-founded Google with Larry Page, and Jimmy Wales co-founded Wikipedia. All three associations are correctly matched.
