Plate Tectonics – NDA Geography PYQs

NDA 2021-I

Q. 1. Which one of the following is not a minor plate?

(a) Cocos Plate

(b) Nazca Plate

(c) Caroline Plate

(d) Antarctic Plate

Answer: (d) Antarctic Plate

Explanation: The Antarctic Plate is one of the seven MAJOR tectonic plates: it is not a minor plate. Cocos Plate (a): a small minor plate in the eastern Pacific Ocean. Nazca Plate (b): a minor plate off the western coast of South America; subducting under the South American plate, creating the Andes. Caroline Plate (c): a small minor plate in the Pacific Ocean near Micronesia. The Antarctic Plate is major: it underlies Antarctica and surrounding ocean. Concept Tested: Antarctic Plate is a MAJOR plate (one of the 7); Cocos, Nazca, and Caroline are minor plates

NDA 2019-II

Q. 2. Which one of the following is a major plate?

(a) Pacific plate

(b) Cocos plate

(c) Arabian plate

(d) Philippine plate

Answer: (a) Pacific Plate

Explanation: There are seven major tectonic plates: Pacific, North American, South American, Eurasian, African, Indo-Australian, and Antarctic. The Pacific Plate is the world’s largest tectonic plate. Cocos Plate, Arabian Plate, and Philippine Plate are all minor (smaller) plates: not included in the seven major plates. Concept Tested: Seven major tectonic plates: Pacific, North American, South American, Eurasian, African, Indo-Australian, Antarctic

★ JOVIK Exam Insight Major vs. minor tectonic plates for NDA: Major plates (7): Pacific, North American, South American, Eurasian, African, Indo-Australian, Antarctic. Minor plates (examples): Cocos, Nazca, Caribbean, Arabian, Philippine, Caroline, Scotia, Juan de Fuca. Remember: Pacific plate is the largest; it is always a major plate. Antarctic plate is also a major plate: a common NDA trap is treating Antarctic as minor.

NDA 2018-I

Q. 3. Which of the following statements about Ring of Fire is/are correct?

1. It is a zone of convergent plate boundaries.

2. It is an active seismic and volcanic zone.

3. It is associated with deep trenches.

Select the correct answer using the code given below:

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 only

(d) 1, 2 and 3

Answer: (d) 1, 2 and 3

Explanation: The Ring of Fire (also called the Circum-Pacific Belt) is a horseshoe-shaped zone around the Pacific Ocean. Statement 1: Correct. The Ring of Fire is predominantly a zone of convergent plate boundaries where oceanic plates are subducting under other plates. There are also some transform fault zones. Statement 2: Correct. The Ring of Fire is the world’s most active seismic and volcanic region: home to about 75% of the world’s active volcanoes and responsible for about 90% of the world’s earthquakes. Statement 3: Correct. The subduction zones of the Ring of Fire produce the world’s deepest ocean trenches: including the Mariana Trench (deepest point on Earth), Tonga Trench, Japan Trench, and Peru-Chile Trench. Concept Tested: Ring of Fire: convergent plate boundaries, most active seismic/volcanic zone, associated with deep trenches

NDA 2013-II

Q. 4. The rigid lithosphere slabs are known as ‘Plates’. What would be the result if the oceanic plate collides with the continental plate?

1. Oceanic plate is forced below the continental plate.

2. Continental plate is forced below the oceanic plate.

3. Continental and oceanic plates never collide.

Select the correct answer using the code given below:

(a) 1 only

(b) 2 only

(c) 1 and 2 only

(d) 1, 2 and 3

Answer: (a) 1 only

Explanation: When an oceanic plate collides with a continental plate, a process called subduction occurs: Statement 1: Correct. The oceanic plate is forced below (subducts under) the continental plate. This happens because the oceanic plate is denser (basaltic, ~3.0 g/cm³) than the continental plate (granitic, ~2.7 g/cm³). The denser plate sinks into the mantle. Statement 2: Incorrect. The continental plate does NOT subduct under the oceanic plate in this scenario; it is the other way around. Statement 3: Incorrect. Continental and oceanic plates do collide: this is one of the primary types of convergent plate boundaries, responsible for features like the Andes Mountains, deep ocean trenches, and coastal volcanoes. Concept Tested: Ocean-continent collision: oceanic plate (denser) subducts under continental plate; creates trenches and volcanic arcs

★ JOVIK Exam Insight Three types of plate boundaries for NDA: 1. Convergent (collision) boundaries: plates move toward each other.    Ocean-Ocean collision: subduction; forms deep trenches and island arcs.    Ocean-Continent collision: ocean subducts; forms trenches, volcanic mountains (e.g., Andes).    Continent-Continent collision: neither subducts; forms fold mountains (e.g., Himalayas, Alps). 2. Divergent boundaries: plates move apart; mid-ocean ridges form (e.g., Mid-Atlantic Ridge). 3. Transform boundaries: plates slide past each other (e.g., San Andreas Fault).

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