Key Concepts & Formulas

10 Practice MCQs

1. Who invented the safety pin in 1849? Options:
   A) Elias Howe B) Walter Hunt C) George Eastman D) Isaac Singer
   Answer: B) Walter Hunt
   Solution: Hunt patented the modern safety pin while trying to pay off a $15 debt.
   Shortcut tip: “Safety first – Hunt for safety.”
   Concept tag: Everyday inventions – 19th-century USA.

2. The first successful polio vaccine (Salk) was introduced in which year? Options:
   A) 1948 B) 1952 C) 1955 D) 1961
   Answer: C) 1955
   Solution: Large-scale trials declared 80-90 % efficacy on 12 Apr 1955.
   Shortcut tip: “Salk = 55 (both have double-5).”
   Concept tag: Medical milestones.

3. Match the invention to the inventor: 1. Dynamo 2. Revolver 3. Barbed wire Options:
   A) 1-Faraday 2-Colt 3-Glidden B) 1-Watt 2-Smith 3-Singer C) 1-Edison 2-Browning 3-Tesla D) 1-Oersted 2-Wesson 3-Howe
   Answer: A) 1-Faraday 2-Colt 3-Glidden
   Solution: Michael Faraday (1831), Samuel Colt (1836), Joseph Glidden (1873).
   Shortcut tip: “FCG – First Class Grade.”
   Concept tag: 19th-century hardware.

4. Which country is associated with the invention of ‘Diesel’ engine? Options:
   A) France B) Germany C) Sweden D) USA
   Answer: B) Germany
   Solution: Rudolf Diesel, patented in 1892 in Munich.
   Shortcut tip: “Diesel sounds German; Mercedes uses it.”
   Concept tag: Power engines.

5. The World Wide Web was first publicly demonstrated at CERN in— Options:
   A) 1989 B) 1991 C) 1993 D) 1995
   Answer: B) 1991
   Solution: Tim Berners-Lee posted the first web page in Aug 1991.
   Shortcut tip: “WWW has 3 W’s; 1991 has 1 & 9 → 1+9+1=11, like twin towers.”
   Concept tag: Digital revolution.

6. Who discovered the phenomenon of radio-activity? Options:
   A) Marie Curie B) Henri Becquerel C) Rutherford D) Einstein
   Answer: B) Henri Becquerel
   Solution: 1896, uranium salts fogged photographic plates.
   Shortcut tip: “Becquerel = ‘Be first’.”
   Concept tag: Nuclear physics.

7. India’s first indigenous satellite, Aryabhata, was launched in— Options:
   A) 1969 B) 1975 C) 1979 D) 1981
   Answer: B) 1975
   Solution: Launched by USSR’s Kosmos-3M rocket on 19 Apr 1975.
   Shortcut tip: “75 = India’s 25th year of independence + 50.”
   Concept tag: Indian Space.

8. The ‘Black box’ flight recorder was invented by— Options:
   A) USA B) Australia C) UK D) Canada
   Answer: B) Australia
   Solution: Dr David Warren, 1953, Melbourne.
   Shortcut tip: “Black box → Aussie ‘black’ box jellyfish country.”
   Concept tag: Aviation safety.

9. Which company released the first commercial digital camera (0.01 MP) in 1991? Options:
   A) Kodak B) Nikon C) Canon D) Sony
   Answer: A) Kodak
   Solution: Kodak DCS-100, priced $20 k.
   Shortcut tip: “Kodak moment → first moment.”
   Concept tag: Imaging tech.

10. ‘Bakelite’, the first fully synthetic plastic, was invented by— Options:
    A) Wallace Carothers B) Leo Baekeland C) Hermann Staudinger D) Alexander Parkes
    Answer: B) Leo Baekeland
    Solution: 1907, USA; patent filed Dec 1909.
    Shortcut tip: “Baekeland → Bake-lite.”
    Concept tag: Materials science.

5 Previous Year Questions

[RRB NTPC 2021] Who is credited with inventing the lift/elevator safety brake? Options:
A) Elisha Otis B) Werner von Siemens C) Thomas Alva Edison D) George Westinghouse
Answer: A) Elisha Otis
Solution: 1852 safety brake demonstration made passenger elevators viable.
Shortcut tip: “OTIS lifts still carry his name.”

[RRB JE 2019] Match: A. Dynamo B. Electric bulb C. Steam engine Options:
A) 1-Watt 2-Edison 3-Faraday B) 1-Faraday 2-Edison 3-Watt C) 1-Edison 2-Watt 3-Faraday D) 1-Watt 2-Faraday 3-Edison
Answer: B) 1-Faraday 2-Edison 3-Watt
Solution: Basic GK triad.
Shortcut tip: “F-E-W → FEW people changed the world.”

[RRB Group-D 2018] X-ray was discovered by— Options:
A) Becquerel B) Roentgen C) Thomson D) Rutherford
Answer: B) Roentgen
Solution: 8 Nov 1895, Würzburg, Germany.
Shortcut tip: “X looks like R (Roentgen) rotated.”

[RRB ALP 2018] India’s first nuclear reactor ‘Apsara’ went critical in— Options:
A) 1956 B) 1958 C) 1960 D) 1962
Answer: A) 1956
Solution: 4 Aug 1956, BARC Trombay.
Shortcut tip: “56 = 5+6 = 11, like 1+1 first reactor.”

[RRB NTPC 2016] Which invention is associated with Guglielmo Marconi? Options:
A) Telephone B) Telegraph C) Radio telegraphy D) Television
Answer: C) Radio telegraphy
Solution: First trans-Atlantic wireless signal 1901.
Shortcut tip: “Mar-cone-i → coned the radio waves.”

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