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Chapter 12: Water (Oceans) MCQs

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Class 11 • Geography

Chapter 12: Water (Oceans)

Source: NCERT Official Textbook

This chapter explores the fundamental role of water on Earth, focusing on the oceans. It begins by highlighting water as a vital, cyclic resource and describes the Hydrological Cycle—the continuous movement of water between the oceans, atmosphere, land, and living organisms.

This cycle is crucial for sustaining life, but increasing demand and pollution are leading to a global water crisis. The second major section details the Relief of the Ocean Floor, revealing a topography as varied as that on land. The ocean floor is divided into four major divisions: the shallow Continental Shelf, the steep Continental Slope, the vast and flat Deep Sea Plain, and the extremely deep Oceanic Deeps or Trenches.

The chapter also explains minor features like Mid-Oceanic Ridges, Seamounts, Submarine Canyons, Guyots (flat-topped seamounts), and Atolls (coral islands). Finally, the chapter examines the physical properties of seawater: Temperature and Salinity.

It analyzes the factors affecting ocean temperature distribution, such as latitude, land/water distribution, winds, and currents, and explains the vertical temperature profile featuring the Thermocline.

Salinity—the total dissolved salts in seawater—is defined, and its horizontal and vertical variations are discussed in relation to evaporation, precipitation, river inflow, and ocean currents. The chapter underscores the interrelationship between the ocean’s physical properties and its role in the Earth’s systems.

Topics Covered:

Section A: Descriptive Questions

  1. What is the hydrological cycle? Describe its significance. (Pg. 2) Page 100
  2. What are the four major divisions of the ocean floors? (Pg. 3) Page 101
  3. Why are continental shelves significant? What covers them? (Pg. 3) Page 101
  4. What are oceanic deeps or trenches? Why are they significant in the study of plate movements? (Pg. 4) Page 102
  5. List the factors affecting the temperature distribution of ocean water. (Pg. 5) Page 103
  6. Describe the three-layer temperature structure of oceans in middle and low latitudes. (Pg. 5-6) Page 103-104
  7. What is salinity? How is it expressed? (Pg. 6) Page 104

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Section B1: Objective MCQs

Page 100

The hydrological cycle describes the movement of water: (Pg. 2)

A) Only in the atmosphereB) Only on landC) On, in, and above the earthD) Only in the oceans
View Answer
Correct Answer: C
Reference: NCERT Page 100
Page 101

Which is the shallowest part of the ocean with an average gradient of 1° or less? (Pg. 3)

A) Continental SlopeB) Deep Sea PlainC) Continental ShelfD) Oceanic Deep
View Answer
Correct Answer: C
Reference: NCERT Page 101
Page 102

The continental slope connects the: (Pg. 4)

A) Ocean basins and oceanic deepsB) Continental shelf and ocean basinsC) Mid-ocean ridges and guyotsD) Deep sea plain and trenches
View Answer
Correct Answer: B
Reference: NCERT Page 102
Page 102

Which ocean has the highest number of explored deeps? (Pg. 4)

A) Atlantic OceanB) Indian OceanC) Pacific OceanD) Arctic Ocean
View Answer
Correct Answer: C
Reference: NCERT Page 102
Page 103

What is a flat-topped seamount called? (Pg. 5)

A) AtollB) GuyotC) CanyonD) Trench
View Answer
Correct Answer: B
Reference: NCERT Page 103
Page 103

Which factor causes upwelling of cold water, lowering coastal temperatures? (Pg. 5)

A) Onshore windsB) Offshore winds (from land to sea)C) Warm ocean currentsD) High latitude
View Answer
Correct Answer: B
Reference: NCERT Page 103
Page 104

Why do oceans in the northern hemisphere record relatively higher temperatures than those in the southern hemisphere? (Pg. 6)

A) More solar insolationB) Larger contact with landC) Weaker ocean currentsD) Less evaporation
View Answer
Correct Answer: B
Reference: NCERT Page 104
Page 104

Which of the following factors does NOT directly affect the surface salinity of oceans? (Pg. 6)

A) EvaporationB) PrecipitationC) Ocean DepthD) River inflow
View Answer
Correct Answer: C
Reference: NCERT Page 104
Page 106

(Exercise) Identify the element which is not a part of the hydrological cycle: (Pg. 8)

A) EvaporationB) HydrationC) PrecipitationD) Condensation
View Answer
Correct Answer: B
Reference: NCERT Page 106
Page 106

(Exercise) The average depth of the continental slope varies between: (Pg. 8)

A) 2-20mB) 200-2,000mC) 20-200mD) 2,000-20,000m
View Answer
Correct Answer: B
Reference: NCERT Page 106
Page 107

(Exercise) Which one is NOT a minor relief feature in the oceans? (Pg. 9)

A) SeamountB) AtollC) Oceanic DeepD) Guyot
View Answer
Correct Answer: C
Reference: NCERT Page 107
Page 107

(Exercise) Salinity is expressed as the amount of salt in grams dissolved in sea water per: (Pg. 9)

A) 10 gmB) 1,000 gmC) 100 gmD) 10,000 gm
View Answer
Correct Answer: B
Reference: NCERT Page 107
Page 107

(Exercise) Which one is the smallest ocean? (Pg. 9)

A) Indian OceanB) Arctic OceanC) Atlantic OceanD) Pacific Ocean
View Answer
Correct Answer: B
Reference: NCERT Page 107

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Section B2: Factual One-Liners

About ______ per cent of the planetary water is found in the oceans. (Pg. 3) Page 101

Reveal Answer
71 (Page 101)

The steep slope where the continental shelf typically ends is called the ______. (Pg. 3) Page 101

Reveal Answer
shelf break (Page 101)

Deep sea plains are the ______ and smoothest regions of the world. (Pg. 4) Page 102

Reveal Answer
flattest (Page 102)

A mountain with a pointed summit rising from the seafloor but not reaching the ocean surface is called a ______. (Pg. 4) Page 102

Reveal Answer
seamount (Page 102)

Low islands in tropical oceans consisting of coral reefs surrounding a central depression are called ______. (Pg. 5) Page 103

Reveal Answer
atolls (Page 103)

The boundary region in the ocean where temperature decreases rapidly with depth is called the ______. (Pg. 5) Page 103

Reveal Answer
thermocline (Page 103)

The average temperature of the ocean surface water is about ______ °C. (Pg. 6) Page 104

Reveal Answer
27 (Page 104)

Salinity is usually expressed as parts per thousand or ______. (Pg. 6) Page 104

Reveal Answer
ppt (Page 104)

(Exercise) The earth is called the ‘Blue Planet’ because of its abundant supply of ______. (Pg. 9) Page 107

Reveal Answer
water (Page 107)

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