NCERT Solutions For Class 11 Geography Chapter 12 Water Oceans - 2025-26

1. Multiple choice questions.

i. Identify the element which is not a part of the hydrological cycle

• (a) Evaporation
• (b) Hydration
• (c) Precipitation
• (d) Condensation

Answer: (b) Hydration.

ii. The average depth of continental slope varies between

• (a) 2–20m
• (b) 200–2,000m
• (c) 20–200m
• (d) 2,000–20,000m

Answer: (b) 200–2,000m.

iii. Which one of the following is not a minor relief feature in the oceans:

• (a) Seamount
• (b) Atoll
• (c) Oceanic Deep
• (d) Guyot

Answer: (c) Oceanic Deep.

iv. Salinity is expressed as the amount of salt in grams dissolved in sea water per

• (a) 10 gm
• (b) 1,000 gm
• (c) 100 gm
• (d) 10,000 gm

Answer: (b) 1,000 gm.

v. Which one of the following is the smallest ocean?

• (a) Indian Ocean
• (b) Arctic Ocean
• (c) Atlantic Ocean
• (d) Pacific Ocean

Answer: (b) Arctic Ocean.

2. Answer the following questions in about 30 words.

i. Why do we call the earth a Blue Planet?

Answer: The Earth is called a Blue Planet because about 71% of its surface is covered with water, mainly in oceans, which makes it appear blue when viewed from space.

ii. What is a continental margin?

Answer: A continental margin refers to the zone of the ocean floor that separates the thin oceanic crust from thick continental crust, including the continental shelf, slope and rise.

iii. List out the deepest trenches of various oceans.

Answer: The deepest trenches include: the Mariana Trench (Pacific Ocean), Puerto Rico Trench (Atlantic Ocean), Java Trench (Indian Ocean), and the Eurasian Basin (Arctic Ocean).

iv. What is a thermocline?

Answer: A thermocline is the layer in the ocean where the temperature decreases rapidly with increasing depth, usually found between the surface warm water and the deep cold water.

v. When you move into the ocean what thermal layers would you encounter? Why the temperature varies with depth?

Answer: You would encounter three layers: the surface warm layer, the thermocline (rapid temperature fall), and the deep cold layer. Temperature varies with depth due to sun’s heat being absorbed at the surface and less light penetrating deeper.

vi. What is salinity of sea water?

Answer: Salinity of sea water refers to the total amount of dissolved salts in sea water, usually measured as grams per 1,000 grams (or parts per thousand - ‰).

3. Answer the following questions in about 150 words.

i. How are various elements of the hydrological cycle interrelated?

Answer: The hydrological cycle describes the continuous movement of water on, in, and above the Earth. Evaporation from oceans and land surfaces turns water into vapor, which rises and cools to form clouds (condensation).

These clouds result in precipitation (rain, snow). Part of the water is absorbed by the ground (infiltration) or returns to oceans via surface runoff and rivers. Ice and snow melt contribute to surface flow, while plant transpiration adds to atmospheric moisture.

All these processes are interdependent, ensuring the renewal and distribution of water across the planet and maintaining ecological balance.

ii. Examine the factors that influence the temperature distribution of the oceans.

Answer: Factors influencing ocean temperature distribution include: latitude (temperature decreases from equator to poles), unequal distribution of land and water (northern hemisphere oceans are warmer), prevailing winds (which can cause upwelling of cold water or pile up warm water), and ocean currents (warm or cold currents impact temperature).

Enclosed seas in low latitudes tend to be warmer, while those in high latitudes are colder. Surface temperature is always highest because the sun’s rays heat the upper layers, and temperature decreases with depth due to limited sunlight penetration.

NCERT Chapter-wise Solutions: Water (Oceans) – Key Concepts

The Water (Oceans) chapter in NCERT Geography deepens your understanding of the hydrological cycle, ocean relief, temperature, and salinity. Mastering these fundamentals is crucial for building a strong base in Geography and performing well in exams.

Regular practice of chapter-wise NCERT solutions helps clarify complex topics like ocean currents, submarine features, and water composition. Focusing on these high-weightage concepts ensures better retention and boosts confidence for competitive exams.

For effective exam prep, revise important diagrams, tables, and flowcharts from the Water (Oceans) NCERT chapter. Apply concise answers, key terms, and examples to increase your accuracy and maximize marks in Geography assessments.

CBSE Class 11 Geography Chapter-wise NCERT Solutions

CBSE Class 11 Geography Study Materials