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Physical Geography

Chapter: Geography

Question 1 of 5 NDA MCQ

 Which of the following statements in respect of landslides are correct?

1. These occur only on gentle slopes duringrain

2. They generally occur in clay–rich soil.

3. Earthquakes trigger landslides.

Select the correct answer using the code givenbelow.

Detailed Explanation

Correct Answer

✓ Option C is correct. Two statements about landslides are accurate.

📖 Core Anchor Concept

Landslides are sudden geological phenomena where rock, soil, and debris move down slopes due to gravitational forces. They are influenced by several factors including slope steepness, soil composition, and triggers like rainfall and earthquakes.

📜 Detailed Breakdown & Chronology

  • Statement 1: Incorrect. Landslides can occur on both gentle and steep slopes, primarily influenced by water saturation in soil.
  • Statement 2: Correct. Landslides often occur in clay-rich soils due to their tendency to become slippery when wet.
  • Statement 3: Correct. Earthquakes can destabilize slopes, triggering landslides as the ground shakes.

The accurate statements regarding landslides, therefore, are 2 and 3. This correlates to option C.

🔍 Option Analysis

  • Option A: Incorrect, as statement 1 is false.
  • Option B: Partially correct, but statement 1 being false makes it incorrect overall.
  • Option D: Incorrect since statement 1 is untrue.

⚡ Chronology Trick / Polity Mnemonic

To remember landslide triggers: Think "Clay and Quake" - clay-rich soils and seismic activity are common precursors.

Landslide Diagram

📖 Factual Verification & Reference

📖 Factual Verification & Reference:

Verified against geology standards and literature, including Earth Science textbooks.

Question 2 of 5 NDA MCQ

Which of the following is the correct ascending order of the given minerals in terms of their presence in the Earth’s crust?

1. Amphibolite

2. Mica

3. Pyroxene

Select the answer using the code given below:

Detailed Explanation
✓

1. Correct Answer

Option C is correct. The correct ascending order is Mica < Amphibolite < Pyroxene.

📖 Core Concept

The question assesses the relative abundance of different minerals in the Earth’s crust, which is a key aspect in geology and material science.

💡 3. Explanation

The relative abundance in the Earth's crust of the minerals listed is as follows:
Mica (4%) < Amphibolite (7%) < Pyroxene (10%)
This data indicates that Pyroxene is the most abundant, followed by Amphibolite, with Mica being the least common among the three minerals. Therefore, the correct ascending order is Mica < Amphibolite < Pyroxene, which corresponds to Option C (2, 1, 3).

❌ 4. Option Analysis

  • •Option A: Incorrect. This suggests Mica is less abundant than Amphibolite which is not accurate.
  • •Option B: Incorrect. This order places Amphibolite as the least abundant mineral.
  • •Option D: Incorrect. This incorrectly ranks Pyroxene as less abundant than Amphibolite.
⚡

NDA Speed-Run / Mnemonic Shortcut

Remember the order of mineral abundance using the initials: "M A P" for Mica, Amphibolite, Pyroxene.

🎯

5. Key Takeaways

Understanding the relative abundance of minerals is crucial in earth sciences and material applications.

Question 3 of 5 NDA MCQ

Which one of the following is formed when volcanic ash is carried by running water and is deposited as a sedimentary layer?

Detailed Explanation
✓

1. Correct Answer

Option D is correct. Tuff is formed from volcanic ash carried by water or wind, then deposited and compacted as a sedimentary rock.

📖 Short Explanation

Tuff is a type of sedimentary rock created when volcanic ash is carried by natural forces like wind or water and deposited in areas, compacted over time, typically near volcanic regions.

💡 3. Why Correct Answer is Correct

Tuff is primarily composed of volcanic ash, produced during explosive volcanic eruptions. As the ash settles, it can be transported by agents such as water or wind. These agents then deposit it as a sedimentary layer, which, over time and under heat and pressure, compacts to form tuff.
Tuff = Volcanic Ash + Water/Wind Transport + Deposition + Compaction

❌ 4. Why Other Options are Wrong

  • •Option A (Basalt): Basalt is an igneous rock formed from the cooling of magma, not a sedimentary deposit from volcanic ash.
  • •Option B (Lapilli): Lapilli are small fragments of lava ejected during an eruption, not specifically related to sedimentary processes involving water transport and deposition.
  • •Option C (Slate): Slate is a metamorphic rock transformed from shale or mudstone, not a direct product of volcanic ash deposition.
⚡

NDA Speed-Run / Mnemonic Shortcut

Remember the phrase "Tough Ashes Form Tuff", linking volcanic ash's role in forming the sedimentary rock tuff.

🎯

5. Key Learning Point

Tuff is a sedimentary rock formed from volcanic ash, indicative of erosion and deposition processes.

6. Visual Suggestion

Illustrate the volcanic ash ejection and deposition process in a diagram showing a volcano, ash clouds, deposition areas, and layers of tuff forming over time.

Question 4 of 5 NDA MCQ

Advantage(s) of tectonic activity in Iceland include(s): (1) Source of natural geothermal energy (2) Creation of new land (3) Attraction of tourists Select the correct answer using the code given below:

Detailed Explanation

Correct Answer

✓ Option D is correct. All listed advantages of tectonic activity apply to Iceland.

📖 Core Anchor Concept

Tectonic activity in Iceland results from its position on the Mid-Atlantic Ridge, where the North American and Eurasian tectonic plates drift apart. This geological setting leads to several benefits.

📜 Detailed Breakdown & Chronology

- **Geothermal Energy**: Iceland is rich in geothermal resources due to volcanic activity. Hot springs and geothermal power plants exploit these resources for sustainable energy. - **Land Creation**: Ongoing volcanic eruptions, such as those from the eruptive systems in the Reykjanes Peninsula, continuously add new land. This land formation significantly alters the landscape. - **Tourism Attraction**: Unique geological formations and geothermal features, such as the Blue Lagoon and geysers, attract millions of tourists annually, contributing to the economy.

🔍 Option Analysis

- **Option A (1 only)**: Incorrect; while geothermal energy is a benefit, it is not the only one. - **Option B (2 and 3 only)**: Incorrect; excludes significant geothermal energy. - **Option C (1 and 3 only)**: Incorrect; excludes land creation through volcanism.

⚡ Chronology Trick / Polity Mnemonic

Remember the acronym **GTL** (Geothermal, Topography, Leisure) to quickly recall the advantages associated with tectonic activity in Iceland.

📖 Factual Verification & Reference

📖 Factual Verification & Reference:

Verified against G.C. Leong’s "Physical Geography" and Icelandic geological studies.

Question 5 of 5 NDA MCQ

Basket-of-eggs topography is related to

Detailed Explanation

Correct Answer

✓ Option (A) is correct. The term relates to Drumlins, which are significant glacial landforms.

📖 Core Anchor Concept

Basket-of-eggs topography describes a type of landscape characterized by Drumlins, which are elongated hills formed by glacial activity.

📜 Detailed Breakdown & Chronology

Drumlins are formed by the deposition of glacial till, shaped by the movement of ice. Key characteristics include:

  • Typical height: 60-100 meters
  • Length: ranges from hundreds of meters up to 1-2 kilometers
  • Appearance: Resemble a cluster of eggs, smooth and rounded

🔍 Option Analysis

  • B - Eskers: These are long, winding ridges formed by sediment deposition from meltwater rivers beneath glaciers.
  • C - Cirques: Bowl-shaped depressions found at the head of a glacier, not related to Drumlins.
  • D - Moraines: Accumulations of debris at the edges of glaciers, differing from drumlins in formation and structure.

⚡ Chronology Trick / Polity Mnemonic

Remember: **D** for Drumlins = **D** for **D**eposition; connect their shape with "B" for Basket semantics.

6. Visual Suggestion

A diagram illustrating Drumlins, showing their elongated shape, clusters resembling eggs, and geographical context in glacial regions.

📖 Factual Verification & Reference

📖 Factual Verification & Reference:

Verified against G.C. Leong, "Physical Geography" for landform characteristics and glacial processes.

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