Q70. Who discovered four of Jupiter’s largest moons through telescopic observations in early 1610?
[SSC CGL – 2022]
(A) Simon Marius
(B) Tycho Brahe
(C) Galileo Galilei
(D) Johannes Kepler
Answer: (C) Galileo Galilei
Explanation: Galileo observed four large moons orbiting Jupiter in January 1610. These Galilean moons—Io, Europa, Ganymede and Callisto—provided evidence that not every celestial object revolves around Earth, strengthening challenges to traditional geocentric astronomy.
Q69. Who developed the modern periodic classification of elements on the basis of atomic number?
[RRB Group D – 2022]
(A) Johann Döbereiner
(B) Dmitri Mendeleev
(C) John Newlands
(D) Henry Moseley
Answer: (D) Henry Moseley
Explanation: Henry Moseley showed in 1913 that atomic number, not atomic mass, provides the correct fundamental order for chemical elements. His X-ray measurements resolved several periodic-table anomalies and underpin the modern periodic law.
Q68. Who invented an early electric battery capable of providing a steady current in 1800?
[SSC CHSL – 2022]
(A) Alessandro Volta
(B) Michael Faraday
(C) Luigi Galvani
(D) Henri Becquerel
Answer: (A) Alessandro Volta
Explanation: Alessandro Volta assembled alternating metal discs separated by brine-soaked material to build the voltaic pile around 1800. This invention supplied a relatively continuous electric current and accelerated experiments in electrochemistry and the study of electricity.
Q67. Who discovered penicillin?
[RRB NTPC – 2021]
(A) Charles Darwin
(B) Alexander Fleming
(C) Gregor Mendel
(D) Louis Pasteur
Answer: (B) Alexander Fleming
Explanation: Fleming found that Penicillium mould prevented nearby bacteria from growing in 1928. Penicillin subsequently became a landmark antibiotic, saving many lives after research teams developed purification, production and clinical applications during the 1940s.
Q66. Who invented the mercury-in-glass thermometer and developed a widely used temperature scale?
[RRB NTPC – 2021]
(A) Anders Celsius
(B) Galileo Galilei
(C) Grand Duke of Tuscany
(D) Daniel Gabriel Fahrenheit
Answer: (D) Daniel Gabriel Fahrenheit
Explanation: Daniel Gabriel Fahrenheit improved mercury thermometers in the early eighteenth century and introduced the Fahrenheit temperature scale. Mercury’s relatively uniform expansion helped make temperature readings reproducible, supporting advances in laboratory science and meteorological measurements.
Q65. Who discovered the major human blood groups?
[RRB NTPC – 2021]
(A) Isaac Newton
(B) Karl Landsteiner
(C) Dmitri Mendeleev
(D) Alexander Fleming
Answer: (B) Karl Landsteiner
Explanation: Karl Landsteiner identified the ABO blood-group system in 1900–1901. His discovery helped explain dangerous reactions during incompatible transfusions and made systematic blood matching possible, transforming the safety of transfusion medicine.
Q64. Who is traditionally credited with inventing paper in ancient China?
[RRB NTPC – 2021]
(A) Baudhayan
(B) Cai Lun
(C) Mahaviracharya
(D) Varahamihira
Answer: (B) Cai Lun
Explanation: Cai Lun is traditionally credited with improving and standardizing papermaking around 105 CE during the Han dynasty. Earlier paper-like materials existed, but the process associated with him helped make inexpensive writing surfaces widely available.
Q63. Who discovered the atomic nucleus?
[RRB NTPC – 2021]
(A) Ernest Rutherford
(B) J. J. Thomson
(C) James Chadwick
(D) Niels Bohr
Answer: (A) Ernest Rutherford
Explanation: Rutherford interpreted the results of the gold-foil scattering experiment in 1911 as evidence of a small, dense, positively charged atomic centre. This nuclear model replaced the earlier plum-pudding concept and opened a new era in atomic physics.
Q62. Who is considered the father of nuclear physics?
[RRB NTPC (2019 recruitment) – 2021]
(A) Niels Bohr
(B) James Chadwick
(C) Ernest Rutherford
(D) J. J. Thomson
Answer: (C) Ernest Rutherford
Explanation: Ernest Rutherford’s research transformed understanding of radioactivity, atomic structure and nuclear transformations. He distinguished types of radiation and developed the nuclear model of the atom. These foundational achievements earned him the widely used title father of nuclear physics.
Q61. What did Douglas Engelbart invent?
[RRB NTPC (2019 recruitment) – 2021]
(A) Compact disc
(B) USB port
(C) Floppy disk
(D) Computer mouse
Answer: (D) Computer mouse
Explanation: Douglas Engelbart demonstrated an early computer mouse in the 1960s as part of research into interactive computing. The pointing device helped people control on-screen interfaces, contributing to later graphical user interfaces and personal-computer interaction.
