Q80. Who discovered the cell nucleus?
[SSC Stenographer – 2024]
(A) Robert Hooke
(B) Antonie van Leeuwenhoek
(C) Robert Brown
(D) James Watson
Answer: (C) Robert Brown
Explanation: Robert Brown described the nucleus in plant cells in 1831. This membrane-bound structure contains most of the genetic material in eukaryotic cells. Hooke had earlier named cells, but did not identify the nucleus as a distinct cellular component.
Q79. Who used microscopes of his own making to observe microorganisms and is often called the father of microbiology?
[SSC Stenographer – 2024]
(A) Matthias Schleiden
(B) Robert Brown
(C) Antonie van Leeuwenhoek
(D) Rudolf Virchow
Answer: (C) Antonie van Leeuwenhoek
Explanation: Antonie van Leeuwenhoek crafted powerful single-lens microscopes and observed bacteria and protozoa in the seventeenth century. He documented these microscopic organisms in letters to the Royal Society, revealing a previously unseen biological world.
Q78. Who arranged the then-known elements so that the properties of every eighth element repeated, proposing the law of octaves?
[SSC Stenographer – 2024]
(A) Johannes van Spronsen
(B) Dmitri Mendeleev
(C) John Newlands
(D) Julius Lothar Meyer
Answer: (C) John Newlands
Explanation: John Newlands proposed the law of octaves in 1865 by arranging elements in increasing atomic mass and noticing periodic repetition after seven intervening elements. The idea worked best for lighter elements and preceded Mendeleev’s more successful periodic arrangement.
Q77. Who reconciled Dalton’s atomic ideas with Gay-Lussac’s law of combining gas volumes by proposing a molecular hypothesis in 1811?
[SSC CGL – 2024]
(A) Robert Boyle
(B) Amedeo Avogadro
(C) Fred Hoyle
(D) Jacques Charles
Answer: (B) Amedeo Avogadro
Explanation: Amedeo Avogadro proposed that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. His hypothesis helped distinguish atoms from molecules and explained regular volume relationships observed in gas reactions.
Q76. Which astronomer is associated with observational evidence that the universe is expanding?
[SSC Stenographer – 2024]
(A) Edwin Hubble
(B) Galileo Galilei
(C) C. V. Raman
(D) James Clerk Maxwell
Answer: (A) Edwin Hubble
Explanation: Edwin Hubble established a relationship between galaxies’ recession velocities and their distances in 1929, strongly supporting cosmic expansion. Earlier theoretical work by Georges Lemaître was also pivotal. This observation became a foundation of modern cosmology.
Q75. Who proposed that every chemical element consists of a distinct kind of atom having its own characteristic mass?
[SSC CGL – 2023]
(A) Antoine Lavoisier
(B) John Dalton
(C) Amedeo Avogadro
(D) Robert Boyle
Answer: (B) John Dalton
Explanation: John Dalton developed his atomic theory in the early nineteenth century. He proposed that each element contains its own kind of atom, distinct in mass and chemical behaviour from those of other elements. Modern science later refined several aspects of this theory.
Q74. Who showed that diborane could reduce aldehydes and ketones via organoboron intermediates to yield alcohols after hydrolysis?
[SSC CGL – 2023]
(A) H. C. Brown
(B) Hugo Rudolph Kruyt
(C) Arthur Stoll
(D) Arne Tiselius
Answer: (A) H. C. Brown
Explanation: Herbert C. Brown advanced boron chemistry and developed useful hydroboration and reduction reactions. His organoborane methods expanded ways to transform organic molecules selectively. Brown shared the 1979 Nobel Prize in Chemistry for work involving organoboron compounds.
Q73. Whose experimental work contributed significantly to the understanding of surface tension and behaviour at liquid interfaces?
[SSC CGL – 2023]
(A) Gerty Cori
(B) Nettie Stevens
(C) Lise Meitner
(D) Agnes Pockels
Answer: (D) Agnes Pockels
Explanation: Agnes Pockels studied surface films and surface tension using experiments devised at home. Her measurements helped establish early surface chemistry, despite her lack of formal university access. Her findings influenced later investigations of monolayers and interfacial phenomena.
Q72. In which year did Tim Berners-Lee invent the World Wide Web, as specified in the examination question?
[SSC CHSL (2022 cycle) – 2023]
(A) 1982
(B) 1995
(C) 1990
(D) 1985
Answer: (C) 1990
Explanation: Tim Berners-Lee proposed the World Wide Web at CERN in 1989 and developed its first working components around 1990. He created foundations including HTML, URLs and HTTP, allowing documents to be linked and accessed across the Internet.
Q71. Who is commonly known as the father of the hydrogen bomb?
[SSC CHSL (memory-based) – 2023]
(A) Wernher von Braun
(B) Edward Teller
(C) Samuel Cohen
(D) None of these
Answer: (B) Edward Teller
Explanation: Edward Teller is widely associated with the development of thermonuclear weapons, particularly work on the Teller–Ulam design alongside Stanislaw Ulam. The label describes his prominent historical role, rather than sole invention by one scientist.
