UPSC Geoscientist

71. Which one among the following is the correct representation of the ele

Which one among the following is the correct representation of the electric field when a conducting spherical shell is placed between the plates of a parallel plate capacitor ?

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Diagram (a)
Diagram (b)
Diagram (c)
Diagram (d)
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The correct option is B.
Inside a conductor in electrostatic equilibrium, the electric field is zero. Electric field lines must be perpendicular to the surface of a conductor. In a parallel plate capacitor, the field is uniform between the plates in the absence of the sphere. When a conducting sphere is introduced, induced charges on its surface redistribute the field lines.
Diagram (b) shows the electric field lines entering and leaving the conducting spherical shell. Key features correctly depicted are:
1. The electric field lines are absent inside the conducting shell, indicating zero electric field within the conductor.
2. The electric field lines are perpendicular to the outer surface of the conducting shell at all points where they meet the surface.
3. The field lines are distorted by the presence of the conductor, originating from the positive plate, terminating on the induced negative charges on the near side of the sphere, originating again from the induced positive charges on the far side of the sphere, and finally terminating on the negative plate.
Diagrams (a) and (d) are incorrect as they show electric fields inside the conductor. Diagram (c) is incorrect as the field lines are not perpendicular to the conductor’s surface.

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72. In a region, the electric potential varies as shown in the figure. Whi

In a region, the electric potential varies as shown in the figure. Which one among the following is the correct representation of the magnitude of the associated electric field ?

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Graph (a)
Graph (b)
Graph (c)
Graph (d)
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The correct option is A.
The electric field E is related to the electric potential V by the equation E = -dV/dx in one dimension. This means the electric field is the negative of the slope of the V-x graph.
In the given potential graph:
– From x=0 to x1, the potential V is constant. The slope dV/dx = 0. Therefore, the electric field E = -0 = 0.
– From x1 to x2, the potential V decreases linearly with increasing x. The slope dV/dx is constant and negative. Therefore, the electric field E = -(negative constant) = a constant positive value.
– From x2 to x3, the potential V is constant. The slope dV/dx = 0. Therefore, the electric field E = -0 = 0.
Graph (a) correctly represents these variations: zero field from 0 to x1, a positive constant field from x1 to x2, and zero field from x2 to x3.

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73. The Chipko Movement was initiated under the leadership of Sunderlal Ba

The Chipko Movement was initiated under the leadership of Sunderlal Bahuguna around the year :

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1951
1971
1981
1991
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The Chipko Movement was a non-violent social and ecological movement by rural villagers, particularly women, in the Uttarakhand region of India (then part of Uttar Pradesh). It aimed to protect trees and forests from logging. Sunderlal Bahuguna was a prominent environmentalist and leader associated with the movement. The question asks for the approximate year the movement was initiated under his leadership.
The Chipko movement originated in the Garhwal Himalayas in the early 1970s. A key incident often cited as igniting the movement occurred in the Reni village in March 1973, where women embraced trees to prevent loggers from felling them. While Chandi Prasad Bhatt was also a significant figure in the movement’s early phase, Sunderlal Bahuguna played a crucial role in giving it wider publicity and spreading its message nationally and internationally. He undertook long foot marches (padyatras) to raise awareness. Although his extensive activism continued for decades, his prominent association and leadership in popularizing the movement began around the early 1970s. Among the given options, 1971 fits within the timeframe of the movement’s initiation and the emergence of its key leaders, including Bahuguna.
The Chipko movement is considered a landmark environmental movement in India, known for its Gandhian methods of non-violent resistance. It inspired subsequent environmental movements and highlighted the importance of community participation in forest conservation.

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74. Which one of the following is the appropriate sequential order of ecol

Which one of the following is the appropriate sequential order of ecological succession ?

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Invasion – Nudation – Competition and coaction – Reaction – Stabilization
Nudation – Invasion – Competition and coaction – Reaction – Stabilization
Nudation – Invasion – Reaction – Competition and coaction – Stabilization
Invasion – Nudation – Competition and coaction – Reaction – Stabilization
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Ecological succession is the process of change in the species structure of an ecological community over time. It typically occurs in a somewhat predictable sequence of stages. The question asks for the correct sequential order of these stages.
The classic sequence of ecological succession (particularly primary succession on bare ground) involves several steps:
1. **Nudation:** The creation of a bare area devoid of life (e.g., by volcanic eruption, glacier retreat, landslide).
2. **Invasion:** The arrival of organisms (propagules like seeds, spores, or larvae) into the bare area. This includes migration and ecesis (establishment and growth).
3. **Competition and Coaction:** Interactions between the established organisms and with the environment, including competition for resources and modifications of the environment.
4. **Reaction:** The established organisms modify the environment (e.g., adding organic matter, changing soil pH, altering light levels), making it more or less suitable for themselves and often creating conditions favorable for the invasion and growth of new species.
5. **Stabilization:** The community reaches a relatively stable state, often referred to as a climax community, where the species composition changes little over time.
Comparing the options with the standard sequence, option B (Nudation – Invasion – Competition and coaction – Reaction – Stabilization) correctly follows the order of the main stages of ecological succession from the initial bare state to a stable community.

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75. Which one among the following group of organisms produces their own fo

Which one among the following group of organisms produces their own food ?

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Autotrophs
Herbivores
Carnivores
Decomposers
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Organisms can be classified based on how they obtain energy and nutrients. The question asks for the group that produces its own food.
– **Autotrophs:** These organisms are capable of producing their own organic compounds (food) from inorganic sources, usually through photosynthesis (using sunlight) or chemosynthesis (using chemical energy). Examples include plants, algae, and some bacteria.
– **Herbivores:** These are heterotrophic consumers that obtain energy by eating plants.
– **Carnivores:** These are heterotrophic consumers that obtain energy by eating other animals.
– **Decomposers:** These organisms, such as bacteria and fungi, obtain energy by breaking down dead organic matter.
Autotrophs form the base of most food chains, producing the initial organic matter that other organisms consume. Herbivores, carnivores, and decomposers are all types of heterotrophs, meaning they rely on consuming other organisms (or their remains) for energy.

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76. Which one of the following pairs of principal chemical constituents in

Which one of the following pairs of principal chemical constituents in water and their source is correct ?

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Ca : Amphiboles, Feldspars, Gypsum
NO₃ : Apatite, Fluorite, Mica
CO₃ : Feldspars, Clay minerals
F : Dolomite, Gypsum, Anhydrite
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This question requires matching common chemical constituents found dissolved in water with their primary source minerals. Water flowing over or through rocks and soil dissolves minerals, contributing to its chemical composition.
– **Calcium (Ca):** Calcium is a common cation in natural waters, often sourced from the dissolution of calcium-bearing minerals. Gypsum (CaSO₄·2H₂O) is a readily soluble mineral containing calcium. Plagioclase feldspars (e.g., anorthite, CaAl₂Si₂O₈) and some amphiboles are silicate minerals that also contain calcium and release it upon weathering. Option A correctly lists common sources of calcium in water.
– **Nitrate (NO₃⁻):** Nitrates are anions usually derived from the nitrogen cycle, including decomposition of organic matter, agricultural fertilizers, and sewage. While nitrogen is present in some minerals (e.g., saltpeter), the significant source of nitrates in water is typically biogeochemical processes and human activities, not the mineral types listed (Apatite – phosphate, Fluorite – fluoride, Mica – silicate). Option B is incorrect.
– **Carbonate (CO₃²⁻):** Carbonates are derived from the dissolution of carbonate rocks like limestone (primarily CaCO₃) and dolomite (CaMg(CO₃)₂). While weathering of silicate minerals like feldspars contributes to alkalinity and the formation of bicarbonate (HCO₃⁻) or carbonate, feldspars and clay minerals themselves are not primary sources of the carbonate ion in the same way carbonate rocks are. Option C is incorrect.
– **Fluoride (F⁻):** Fluoride in natural water often comes from the dissolution of fluoride-bearing minerals like Fluorite (CaF₂), cryolite (Na₃AlF₆), and some micas and apatites. Dolomite, Gypsum, and Anhydrite are calcium/magnesium carbonates or sulfates and are not primary sources of fluoride. Option D is incorrect.
The chemical composition of natural water is largely determined by the geology of the area it flows through and human activities. Understanding the weathering processes and mineral compositions helps identify the origins of dissolved substances. Option A provides the most accurate set of sources for Calcium among the choices.

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77. Which one of the following sequences of electromagnetic spectrum is co

Which one of the following sequences of electromagnetic spectrum is correct in terms of ascending wavelength order ?

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X-rays – Gamma rays – UV – Infrared – Visible – Microwaves – Radio and TV waves
Gamma rays – X-rays – UV – Infrared – Visible – Microwaves – Radio and TV waves
Gamma rays – X-rays – UV – Visible – Infrared – Microwaves – Radio and TV waves
UV – Gamma rays – X-rays – Visible – Infrared – Microwaves – Radio and TV waves
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The electromagnetic spectrum is the range of all types of electromagnetic radiation. These radiations differ in wavelength, frequency, and energy. The question asks for the order of regions of the spectrum in terms of ascending (increasing) wavelength.
The order of the electromagnetic spectrum from shortest wavelength (highest frequency/energy) to longest wavelength (lowest frequency/energy) is:
Gamma rays → X-rays → Ultraviolet (UV) → Visible light → Infrared (IR) → Microwaves → Radio waves.
We need to arrange the given options in increasing wavelength.
Let’s check option C: Gamma rays – X-rays – UV – Visible – Infrared – Microwaves – Radio and TV waves. This sequence correctly lists the regions from shortest wavelength (Gamma rays) to longest wavelength (Radio waves). TV waves are a type of radio wave.
Comparing this with the other options, none of them follow the correct order of increasing wavelength.

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78. Which of the following is a true fish ?

Which of the following is a true fish ?

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Jellyfish
Silverfish
Starfish
Sea horse
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The term “true fish” in a biological context refers to aquatic vertebrates belonging to the superclass Pisces. These animals are characterized by features such as gills for breathing oxygen from water, fins for locomotion, and typically scales. Many animals are commonly called “fish” but do not fit this biological definition.
– **Jellyfish:** These are marine invertebrates belonging to the phylum Cnidaria. They are not fish.
– **Silverfish:** These are small, wingless insects belonging to the order Zygentoma. They are not fish.
– **Starfish:** These are marine invertebrates belonging to the phylum Echinodermata. They are not fish.
– **Sea horse:** Sea horses are marine vertebrates belonging to the genus *Hippocampus*. They are a type of bony fish (class Actinopterygii).
Identifying “true fish” requires understanding basic zoological classification. The common names of many marine invertebrates include “fish” (e.g., shellfish, crayfish), leading to confusion. However, biologically, “fish” refers specifically to the aquatic vertebrates that breathe with gills and have fins.

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79. In which sphere of the atmosphere is harmful ultraviolet (UV) radiatio

In which sphere of the atmosphere is harmful ultraviolet (UV) radiation from the Sun absorbed ?

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Mesosphere
Thermosphere
Troposphere
Stratosphere
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The atmosphere is composed of several layers, each with distinct characteristics regarding temperature, composition, and phenomena. The absorption of harmful ultraviolet (UV) radiation from the Sun primarily occurs in a specific layer.
– The **Stratosphere** contains the ozone layer (O₃). Ozone molecules are highly effective at absorbing UV-B and UV-C radiation from the sun, preventing most of it from reaching the Earth’s surface.
– The Mesosphere is above the stratosphere, where most meteors burn up.
– The Thermosphere is the outermost layer, where temperature rises sharply due to absorption of high-energy radiation, but it’s not the primary layer for absorbing harmful UV-B/C.
– The Troposphere is the lowest layer, where weather occurs, and it absorbs very little UV radiation.
The absorption of UV radiation by the ozone layer in the stratosphere is crucial for protecting life on Earth from the damaging effects of high-energy UV radiation, such as skin cancer and damage to plant life.

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80. Consider the following combinations of lapse rate in relation to atmos

Consider the following combinations of lapse rate in relation to atmospheric region :

  • 1. Troposphere : Negative lapse rate
  • 2. Stratosphere : Negative lapse rate
  • 3. Mesosphere : Negative lapse rate
  • 4. Thermosphere : Positive lapse rate

How many of the combinations given above is/are correct ?

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1
2
3
4
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Lapse rate refers to the rate at which temperature changes with altitude in the atmosphere. A positive lapse rate means temperature decreases with increasing altitude. A negative lapse rate (also known as an inversion) means temperature increases with increasing altitude. We need to examine the temperature profile of each atmospheric layer.
1. **Troposphere:** Temperature generally decreases with altitude (positive lapse rate). Statement 1 is incorrect.
2. **Stratosphere:** Temperature increases with altitude due to the absorption of UV radiation by the ozone layer (negative lapse rate). Statement 2 is correct.
3. **Mesosphere:** Temperature decreases with altitude (positive lapse rate), reaching the coldest temperatures in the atmosphere at the mesopause. Statement 3 is incorrect.
4. **Thermosphere:** Temperature increases significantly with altitude due to the absorption of high-energy solar radiation (negative lapse rate/temperature increasing with height). Statement 4 states positive lapse rate, which is incorrect.
The atmospheric layers are defined based on temperature changes with altitude. The boundaries between layers (tropopause, stratopause, mesopause) are where the temperature trend reverses. Only the Stratosphere and Thermosphere exhibit temperature increases with altitude.

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