Important Questions and Answers for Class 11 Geography Chapter 12 2025-26

1. Which of the following is NOT a component of the hydrological cycle?

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

Answer: (b) Hydration. 

Hydration is not a process in the hydrological cycle; evaporation, condensation, and precipitation are main processes.

2. The average depth of the continental slope ranges between:

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

Answer: (b) 200–2,000 m. 

The continental slope usually ranges from 200 to 3,000 m deep, but mostly falls within 200–2,000 m.

3. Which one of the following is not a minor relief feature in oceans?

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

Answer: (c) Oceanic Deep. 

Oceanic Deeps are major features; seamount, atoll, and guyot are minor features.

4. Salinity of sea water is expressed as grams of salt per:

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

Answer: (b) 1,000 gm. 

Salinity is measured as grams of salt per 1,000 grams (1 litre) of sea water.

5. Which of the following is the smallest ocean?

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

Answer: (b) Arctic Ocean. 

The Arctic Ocean is the smallest among all oceans on Earth.

2. Very Short Answer (VSA).

1. Why is Earth called the “Blue Planet”?

Answer: Earth is called the “Blue Planet” because about 71% of its surface is covered by water, mainly the vast oceans, giving it a blue appearance from space.

2. What is a thermocline?

Answer: A thermocline is a layer in the ocean, usually found between 100–400 m depth, where temperature decreases rapidly with increasing depth.

3. Name any two minor relief features of the ocean floor.

Answer: Two minor relief features of the ocean floor are seamounts and atolls; both are unique underwater landforms shaped by volcanic and biological processes.

4. What is salinity?

Answer: Salinity is the total content of dissolved salts in sea water, usually expressed as parts per thousand (‰ or ppt).

5. Write one factor affecting ocean temperature.

Answer: Latitude affects ocean temperature; surface water temperature generally decreases from the equator toward the poles due to reduced solar energy.

3. Short Answer Questions.

1. State two ways in which temperature varies with ocean depth and explain why.

Answer: Temperature in oceans is highest at the surface due to direct sunlight and decreases with depth. The upper layer is warm, followed by a rapid drop in the thermocline. Below this, temperature remains close to freezing as sunlight cannot penetrate deeper layers. Salinity and density also influence heat distribution.

2. How does the hydrological cycle maintain water balance on Earth?

Answer: The hydrological cycle allows continuous circulation of water between oceans, land, and atmosphere through evaporation, condensation, precipitation, and runoff. This constant exchange ensures water is reused and helps balance freshwater and ocean water on Earth over time.

3. Why does the Bay of Bengal have lower salinity compared to the Arabian Sea?

Answer: Bay of Bengal has lower salinity due to the large influx of river water from several major rivers. The Arabian Sea’s salinity is higher because of less freshwater addition and high evaporation rates.

4. Long Answer Questions.

1. Explain the major divisions of the ocean floor and their characteristics.

Answer: The ocean floor consists of four major divisions: continental shelf, continental slope, deep sea plain, and oceanic deeps. The continental shelf is a gently sloping, shallow region extending from the shore, rich in sediments and marine resources. Next is the continental slope, marked by a steeper drop, reaching depths of 200–3,000 m, often with canyons and trenches. The deep sea plain is a broad, flat area, covering much of the ocean floor with fine sediments. Oceanic deeps or trenches are narrow, deep troughs, formed due to tectonic activity and representing the greatest ocean depths.

1. Continental shelf: shallow, rich in resources.
2. Continental slope: steep slope, end of continent.
3. Deep sea plain: flat, sediment-covered region.
4. Oceanic deeps: narrow, deepest sections formed by tectonics.

2. Analyze the factors influencing the horizontal and vertical distribution of temperature in the world’s oceans.

Answer: The horizontal distribution of ocean temperature is mainly affected by latitude—temperatures are higher at the equator and decrease towards the poles. Areas close to land, prevailing winds, and ocean currents modify local temperatures. Vertically, surface layers are warmer due to sunlight. A layer called thermocline shows a rapid drop in temperature, below which water becomes cold and uniform. Factors like salinity and density difference also play a role in vertical variation. Warm ocean currents and wind movement further influence both horizontal and vertical temperature patterns.

1. Latitude and incoming solar energy
2. Presence of land masses
3. Prevailing winds and ocean currents
4. Layered structure: warm surface, thermocline, cold deep water

5. Assertion–Reason type questions.

Assertion (A): The temperature in the ocean drops sharply up to a certain depth and then remains almost constant.
Reason (R): The thermocline is a rapid temperature transition layer in oceans found below the warm surface water.

• (a) A and R are true, and R is the correct explanation of A
• (b) A and R are true, but R is not the correct explanation of A
• (c) A is true, but R is false
• (d) A is false, but R is true

Answer: (a) A and R are true, and R correctly explains A. The thermocline causes a sharp drop in temperature with depth.

Why learning oceanography helps Class 11 Geography students?

Exploring class 11 geography chapter 12 important questions and answers deepens your understanding of the hydrological cycle and ocean features. These topics simplify concepts in geography chapter 11 Water (Oceans) and prepare you for diagram-based questions and world geography chapter 12 test answers.

Topics like thermocline and salinity connect directly to real-life observations. Understanding them through geography chapter 11 quizlet style revision makes remembering facts easier. Focus on minor relief features, oceanic currents, and relief for better results in map and concept-based questions.