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Railway RRB / NTPC

Railway RRB & NTPC MCQ questions — GK, Math, Reasoning, General Science.

1,954 Q 4 Subjects 10th / Graduate
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Difficulty: All Easy Medium Hard 1941–1950 of 1,954
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Q.1941 Easy General Science Botany
Photosynthesis occurs in?
A Root
B Stem
C Leaf
D Flower
Correct Answer:  C. Leaf
EXPLANATION

In chloroplasts of leaves.

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Q.1942 Easy General Science Physics
Newton first law also called?
A Law of acceleration
B Law of gravitation
C Law of inertia
D Law of reaction
Correct Answer:  C. Law of inertia
EXPLANATION

First law = Law of Inertia.

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Q.1943 Easy General Science Human Body
Organ that pumps blood?
A Liver
B Kidney
C Heart
D Lungs
Correct Answer:  C. Heart
EXPLANATION

Heart pumps blood.

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Q.1944 Easy General Science Chemistry
Chemical formula of water?
A HO
B H2O
C H2O2
D HO2
Correct Answer:  B. H2O
EXPLANATION

Water = H₂O.

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Q.1945 Medium General Science Space & Astronomy
The James Webb Space Telescope observes primarily in which wavelength region of the electromagnetic spectrum, and what is the key advantage of this choice?
A Ultraviolet; better for observing hot, young stars
B Visible light; provides clearest images of the universe
C Infrared; allows observation through cosmic dust and enables viewing of early universe objects
D Microwave; measures the cosmic microwave background radiation directly
Correct Answer:  C. Infrared; allows observation through cosmic dust and enables viewing of early universe objects
EXPLANATION

The James Webb Space Telescope operates primarily in infrared wavelengths (0.6-28 micrometers), which penetrates dust clouds that block visible light, allowing it to observe star-forming regions, protoplanetary disks, and extremely distant galaxies from the early universe.

Infrared observations also reveal objects too cool or distant to be seen in visible light, making it superior for studying the universe's earliest structures and most distant objects.

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Q.1946 Medium General Science Space & Astronomy
What is the primary reason why Venus experiences a runaway greenhouse effect compared to Earth, despite being only slightly closer to the Sun?
A Venus has a much thicker atmosphere composed primarily of carbon dioxide with clouds of sulfuric acid
B Venus rotates much faster than Earth, trapping more heat
C Venus lacks a magnetic field to protect it from solar radiation
D Venus is larger in size and therefore has greater gravitational compression
Correct Answer:  A. Venus has a much thicker atmosphere composed primarily of carbon dioxide with clouds of sulfuric acid
EXPLANATION

Venus's dense atmosphere (90 times denser than Earth's) is composed of 96.5% carbon dioxide with clouds of concentrated sulfuric acid, creating an extreme greenhouse effect with surface temperatures around 465°C.

This massive atmospheric composition traps far more infrared radiation than Earth's atmosphere, making it the primary cause of Venus's extreme greenhouse conditions rather than its orbital position alone.

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Q.1947 Hard General Science Space & Astronomy
Which of the following statements about the Oort Cloud is incorrect?
A It is a theoretical spherical shell of icy bodies surrounding our solar system
B It extends approximately 100,000 to 200,000 AU from the Sun
C It is the primary source of long-period comets
D It has been directly observed through telescopes and contains approximately 1 trillion objects
Correct Answer:  D. It has been directly observed through telescopes and contains approximately 1 trillion objects
EXPLANATION

The Oort Cloud remains theoretical and has never been directly observed; we infer its existence from comet trajectories and orbital studies.

While estimates suggest it contains billions to trillions of icy bodies, these objects are too distant and too small to be directly observed with current technology, making option D the incorrect statement among the given choices.

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Q.1948 Medium General Science Physics
The escape velocity from the surface of a planet depends on which two fundamental properties of that planet?
A Radius and temperature
B Mass and radius
C Density and temperature
D Atmospheric pressure and mass
Correct Answer:  B. Mass and radius
EXPLANATION

Escape velocity is mathematically derived as v = √(2GM/R), where G is gravitational constant, M is the planet's mass, and R is its radius.

These two properties directly determine the gravitational field strength at the planet's surface, which defines the minimum velocity needed to escape gravitational attraction.

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Q.1949 Easy General Science Space & Astronomy
Which celestial phenomenon occurs when the Moon passes between the Earth and the Sun, blocking the Sun's light and casting a shadow on Earth?
A Solar Eclipse
B Lunar Eclipse
C Penumbral Eclipse
D Annular Eclipse
Correct Answer:  A. Solar Eclipse
EXPLANATION

A solar eclipse happens when the Moon's orbit places it directly between Earth and the Sun, creating a shadow on Earth's surface.

This is distinct from a lunar eclipse where Earth blocks sunlight from reaching the Moon, and from penumbral or annular eclipses which are specific types with different characteristics.

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Q.1950 Hard General Science Chemistry
Which of the following substances will have the lowest lattice enthalpy among ionic compounds?
A NaCl
B MgO
C CsI
D CaF₂
Correct Answer:  C. CsI
EXPLANATION

Lattice enthalpy depends inversely on ionic radius and directly on ionic charge.

CsI has the lowest lattice enthalpy (~604 kJ/mol) because both Cs⁺ and I⁻ are large ions with 1+ and 1- charges respectively.

In contrast, MgO has very high lattice enthalpy due to small, highly charged ions (Mg²⁺ and O²⁻), while NaCl and CaF₂ have intermediate values.

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