Environmental Geosciences MCQ Quiz in मल्याळम - Objective Question with Answer for Environmental Geosciences - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The correct answer is Two plates move away from one another.

Key Points

• The mid-ocean ridge is the most extensive chain of mountains on Earth, stretching nearly 65,000 kilometres (40,390 miles) and with more than 90% of the mountain range lying underwater, in the deep ocean.
• The massive mid-ocean ridge system is a continuous range of underwater volcanoes that wraps around the globe like seams on a baseball, stretching nearly 65,000 kilometres (40,390 miles).
• The majority of the system is underwater, with an average water depth to the top of the ridge of 2,500 meters (8,200 feet).
• Mid-ocean ridges occur along divergent plate boundaries, where the new ocean floor is created as the Earth’s tectonic plates spread apart.
• A divergent boundary occurs when two tectonic plates move away from each other.
• As the plates separate, the molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
• The speed of spreading affects the shape of a ridge – slower spreading rates result in steep, irregular topography while faster-spreading rates produce much wider profiles and more gentle slopes.

Therefore, the correct answer is two plates move away from one another.

Additional InformationA divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth’s mantle to the surface, solidifying to create a new oceanic crust. The Mid-Atlantic Ridge is an example of divergent plate boundaries.

When two plates come together, it is known as a convergent boundary. The impact of the colliding plates can cause the edges of one or both plates to buckle up into mountain ranges or one of the plates may bend down into a deep seafloor trench. The Pacific Ring of Fire is an example of a convergent plate boundary.

Two plates sliding past each other form a transform plate boundary. One of the most famous transform plate boundaries occurs at the San Andreas fault zone, which extends underwater.

The correct answer is N2 and O2.

Key Points

• The atmosphere contains many gases, most in small amounts, including some pollutants and greenhouse gases. 
• The most abundant gas in the atmosphere is nitrogen, with oxygen second and argon, an inert gas the third most abundant gas in the atmosphere.
• The atmosphere is composed of a mix of several different gases in differing amounts. 
• The permanent gases whose percentages do not change from day to day are nitrogen, oxygen and argon. 
• Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%. 
• Gases like carbon dioxide, nitrous oxides, methane, and ozone are trace gases that account for about a tenth of 1% of the atmosphere. 
• Water vapour is unique in that its concentration varies from 0-4% of the atmosphere depending on where you are and what time of the day it is.

Therefore, the correct answer is N2 and O2.

The correct answer is Statement 1 is true, but Statement 2 is false.

Key Points

Statement I: Freshwater is less dense than saltwater, which causes it to float above saltwater in coastal aquifers, is true because,-

• Density Difference: Freshwater and saltwater have different densities, with freshwater having a lower density (approximately 1.00 g/cm³) compared to saltwater (approximately 1.025 g/cm³).
• Stratification: This difference in density causes stratification in coastal aquifers, where freshwater forms a lens above the denser saltwater.
• Buoyancy Effect: The lower density of freshwater leads to a buoyancy effect where it naturally tends to float on top of the denser saltwater.
• This phenomenon is critical in coastal hydrogeology and helps in understanding the behavior of freshwater lenses in coastal regions.
• Interface Zone: The zone where freshwater and saltwater meet in an aquifer is called the freshwater-saltwater interface or transition zone and is often characterized by a mixing of the two water types.

Statement II: The Ghyben-Herzberg relation is used to calculate the relative density of freshwater and saltwater, is false because,-

• The Ghyben-Herzberg relation is not used to calculate the densities of freshwater and saltwater but rather focuses on the depth of the freshwater-saltwater interface.
• The Ghyben-Herzberg principle describes a hydrostatic equilibrium where fresh groundwater floats above saline water in coastal aquifers.
• It provides a simple mathematical relationship to estimate the depth of the interface below sea level: h = 40*H, where h is the depth of the saltwater-freshwater interface below sea level, and H is the height of the water table above sea level.
• This relationship is based on the difference in density between freshwater and saltwater but does not directly calculate their densities.

Additional Information

• Coastal Aquifers: Coastal aquifers are significant sources of freshwater, especially in areas where surface water resources are limited.
• Saltwater Intrusion: Understanding the freshwater-saltwater interface is essential for managing saltwater intrusion, which can threaten freshwater supplies in coastal areas.
• Impacts of Over-extraction: Over-extraction of freshwater can cause a rise in the interface, leading to contamination of freshwater reserves with saltwater.
• The calculation and monitoring of the freshwater-saltwater boundary using the Ghyben-Herzberg principle help in sustainable groundwater management.

The correct answer is C, B, D, E, and A.

Key Points

• The Goldich dissolution series is a method of predicting the relative stability or weathering rate of common igneous minerals on the Earth's surface, with minerals that form at higher temperatures and pressures less stable on the surface than minerals that form at lower temperatures and pressures. 
• The Goldich dissolution series concerns intrinsic mineral qualities, which were proven both by Goldich as well as preceding scientists to also be important for constraining weathering rates.
• According to the series, the increasing order of stability for weathering is:
  • ​Calcite, Olivine, Ca rich feldspar, Na rich feldspar and Illite.

Therefore, the correct answer is C, B, D, E, and A.

The correct answer is A, B, E, D, and C.

Key Points

• In the case of the interpretation of satellite images, the characteristics of objects are studied regarding single or multiple spectral bands because there is generally more than one image acquired in different spectral regions of the electromagnetic spectrum. 
• Image interpretations employ a combination of the following elements:
  1. Location
  2. Tone
  3. Size
  4. Shape
  5. Texture
  6. Association
  7. Shadow
  8. Site, and
  9. Pattern.
  10. Situation
• The elements in the order of their complexity are Location, Tone, Texture, Pattern and Situation.

Therefore, the correct answer is A, B, E, D, and C.

Additional Information

The correct answer is Humic and fulvic acids in humus form hydrophobic colloids whereas clay colloids are hydrophilic in nature.

 Key PointsConsider the first statement: Humus represents organic matter, dark in colour.

• Humus is dark, organic material that forms in soil when plant and animal matter decays.
• The thick brown or black substance that remains after most of the organic litter has decomposed is called humus.

Thus the first statement is correct.

Consider the second statement: Acid soils are devoid of basic cations.

• The acidity of the soil is due to the predominance of H+ ions over OH– ions, the bulk of H+ ions being held in close association with the clay-organic colloid complex. 
• So acid soils lack basic cations.

Thus the second statement is correct.

Consider the third statement: Humus contains cellulose and hemicellulose.

• Humus can be defined as a lingo protein complex containing approximately 45 % - lignin compounds, 35% - amino acids, 11% - carbohydrates, 4% - cellulose, 7% - Hemicellulose, 3% - fats, wax, and resins, 6% - other miscellaneous substances, including plant growth substances and inhibitors.

Thus the third statement is correct.

Consider the fourth statement: Humic and fulvic acids in humus form hydrophobic colloids whereas clay colloids are hydrophilic in nature.

• The polycyclic functional groups of humic acid molecules hold or “chelate” water.
• Humates hold many times their weight in moisture and they are not repellant, even when dry.
• This makes humic acids hydrophilic, not hydrophobic (resistant to or avoiding wetting).
• Natural colour is primarily due to the presence of humic substances classified as humic and fulvic acids.
• These are colloidal, hydrophilic, anionic polymeric compounds which are refractive (non-biodegradable).
• Colloidal clay particles are considered as occupying an intermediate position being neither truly lyophilic (liquid-loving) or hydrophilic (water-loving) nor lyophobic (liquid-hating) or hydrophobic (water-repellent).
• Clay colloids possess the properties hydrophilic because of their hydration.

Thus the fourth statement is incorrect.

Therefore, the correct answer is humic and fulvic acids in humus form hydrophobic colloids whereas clay colloids are hydrophilic in nature.

Explanation:

• La Nina is a Spanish word meaning "the girl" or "the little girl."
• It is also used to describe a climate pattern that affects the tropical Pacific Ocean.
• La Niña is the opposite of El Niño and is characterized by cooler-than-normal sea surface temperatures in the central and eastern tropical Pacific Ocean.
• La Niña episodes, which can last up to 12 months, are associated with an increased chance of below-average precipitation in the southwestern United States, including California and Arizona. La Niña episodes can also cause changes in temperature and precipitation patterns around the world.

The correct answer is: A-2, B-1, C-3, D-4

Key Points

Additional Information

• Moho Discontinuity:
  • Definition: The Moho Discontinuity, or Mohorovičić Discontinuity, marks the boundary between Earth's crust and the mantle.
  • Characteristics: Discovered by Andrija Mohorovičić, it represents a change in seismic wave velocities. P-waves and S-waves increase in velocity at this boundary due to the transition from less dense rocks of the crust to denser rocks of the mantle.
  • Location: Found at varying depths: typically about 35 kilometers (22 miles) beneath continents and around 5 to 10 kilometers (3 to 6 miles) beneath ocean floors.
• Gutenberg Discontinuity:
  • Definition: The Gutenberg Discontinuity is the boundary between Earth's mantle and outer core.
  • Characteristics: Discovered by Beno Gutenberg, it is identified by a sudden drop in the velocity of S-waves, which cannot travel through liquids, indicating the outer core is molten. P-waves also slow down and refract at this boundary.
  • Location: Occurs at a depth of about 2900 kilometers (1800 miles) below the Earth's surface.
• Lehmann Discontinuity:
  • Definition: The Lehmann Discontinuity marks the boundary between Earth's outer and inner core.
  • Characteristics: Discovered by Inge Lehmann, this discontinuity is characterized by an increase in P-wave velocities due to the transition from the liquid outer core to the solid inner core.
  • Location: Found at a depth of about 5160 kilometers (3200 miles).
• Conrad Discontinuity:
  • Definition: The Conrad Discontinuity is the boundary between the upper and lower parts of the Earth's crust.
  • Characteristics: It signifies a transition between different types of crustal materials, typically with a slight change in seismic velocity.
  • Location: Depth varies, generally found between 15 and 20 kilometers (9 to 12 miles) beneath continental crust.

The correct answer is: 1 - D → A → C → B

Physical weathering is a geological process where rocks disintegrate without any chemical alteration. It's primarily driven by the physical forces that cause rocks to break apart into smaller fragments. Among the various mechanisms of physical weathering, thermal expansion and contraction play a crucial role, especially in regions experiencing significant temperature variations between day and night.

Key Points

Processes of Physical Weathering in Order:

• Thermal Expansion and Contraction (D):
  • Occurs when rocks are subjected to extreme temperature changes.
  • During day, rocks expand due to heat, and during night, they contract as temperatures drop.
  • This repetitive cycle eventually stresses the rock material.
• Formation of Cracks due to Differential Expansion (A):
  • Different minerals within the rock expand and contract at different rates.
  • This leads to the development of internal stresses and the formation of cracks.
  • Over time, these stress fractures become more pronounced.
• Peeling off of the Surface Layer (Exfoliation) (C):
  • As the surface layers crack, they start to detach from the underlying layers.
  • This process is known as exfoliation, where thin layers or sheets of rock peel off.
  • Commonly observed in granitic rocks subjected to intense temperature variations.
• Disintegration of Rock into Smaller Pieces (B):
  • Once exfoliation occurs, the rock begins to disintegrate into smaller fragments.
  • These smaller pieces can be further broken down by other weathering processes.
  • Ultimately, this leads to the formation of soil and sediment.

Additional Information

• Physical weathering does not alter the mineral composition of the rock, unlike chemical weathering, which involves chemical changes.
• This process is more effective in environments with strong temperature fluctuations, such as deserts and mountainous regions.
• Other forms of physical weathering include frost wedging, salt crystallization, and pressure release or unloading.
• Physical weathering is a crucial first step in soil formation and plays a significant role in shaping the Earth's landscape.

The correct answer is A - III, B - I, C - IV, D - II.

Key Points

Therefore, the correct answer is A - III, B - I, C - IV, and D - II. Additional Information

•  A geologic hazard or geohazard is an adverse geologic condition capable of causing widespread damage or loss of property and life.
• Geohazards can be relatively small features, but they can also attain huge dimensions (e.g., submarine or surface landslide) and affect local and regional socio-economics to a large extent (e.g., tsunamis).
• Chemical hazards and toxic substances pose a wide range of health hazards (such as irritation, sensitization, and carcinogenicity) and physical hazards (such as flammability, corrosion, and explosibility).
• Hydrometeorological hazards—including floods, droughts, landslides, and storm surges—threaten lives and impact livelihoods.
• Biological health hazards include bacteria, viruses, parasites and moulds or fungi. They can pose a threat to human health when they are inhaled, eaten or come in contact with skin.