Water (Oceans) Important Questions
These Water (Oceans) Important Questions cover important NCERT concepts related to oceans, ocean relief features, salinity, ocean temperature, waves, tides and ocean currents.
The chapter-wise questions include MCQs, one-word questions, assertion and reason questions and analytical descriptive questions useful for UPSC, SSC, Railways, State PSC, CUET, CBSE board exams and competitive examinations.
NCERT Page Coverage: Page 104–111
Table of Contents
Multiple Choice Questions (MCQs)
These MCQs from Water (Oceans) help students revise important oceanographic concepts related to ocean relief, salinity, tides, waves and ocean currents.
MCQ 1
About how much percentage of Earth’s surface is covered by water?
- A. 51%
- B. 61%
- C. 71%
- D. 81%
Page Reference: Page 104
MCQ 2
The Pacific Ocean is the:
- A. Smallest ocean
- B. Deepest and largest ocean
- C. Warmest ocean only
- D. Saltiest ocean only
Page Reference: Page 104
MCQ 3
The average depth of oceans is approximately:
- A. 1000 metres
- B. 2500 metres
- C. 3800 metres
- D. 7000 metres
Page Reference: Page 104
MCQ 4
The continental shelf is:
- A. Deep ocean trench
- B. Gently sloping submerged extension of continent
- C. Mid-ocean ridge
- D. Volcanic island only
Page Reference: Page 105
MCQ 5
The continental slope connects:
- A. Ocean trenches and ridges
- B. Continental shelf and deep ocean floor
- C. Islands and coral reefs
- D. Rivers and deltas only
Page Reference: Page 105
MCQ 6
The deep ocean floor is also called:
- A. Abyssal plain
- B. Continental shelf
- C. Lagoon
- D. Coral reef
Page Reference: Page 105
MCQ 7
The Mariana Trench is located in:
- A. Atlantic Ocean
- B. Indian Ocean
- C. Pacific Ocean
- D. Arctic Ocean
Page Reference: Page 106
MCQ 8
Mid-oceanic ridges are mainly formed due to:
- A. Sediment deposition
- B. Plate tectonic activity
- C. River erosion
- D. Coral growth only
Page Reference: Page 106
MCQ 9
Ocean water salinity is measured in:
- A. Percentages only
- B. Parts per thousand
- C. Kilometres
- D. Degrees Celsius
Page Reference: Page 107
MCQ 10
Average salinity of ocean water is about:
- A. 15‰
- B. 25‰
- C. 35‰
- D. 50‰
Page Reference: Page 107
MCQ 11
Salinity increases with:
- A. Heavy rainfall
- B. River inflow
- C. High evaporation
- D. Ice melting only
Page Reference: Page 107
MCQ 12
Ocean temperature decreases with increasing:
- A. Salinity only
- B. Depth
- C. Wind speed only
- D. Tides only
Page Reference: Page 108
MCQ 13
The boundary separating warm surface water and cold deep water is called:
- A. Thermocline
- B. Halocline
- C. Pycnocline
- D. Shelf break
Page Reference: Page 108
MCQ 14
Horizontal movement of ocean water is called:
- A. Tide
- B. Ocean current
- C. Wave
- D. Tsunami
Page Reference: Page 109
MCQ 15
Warm ocean currents generally move from:
- A. Poles to equator
- B. Equator to poles
- C. East to west only
- D. West to east only
Page Reference: Page 109
MCQ 16
The Gulf Stream is a:
- A. Cold current
- B. Warm current
- C. Polar current
- D. Tidal current only
Page Reference: Page 109
MCQ 17
The Labrador Current is a:
- A. Warm current
- B. Cold current
- C. Equatorial current
- D. Monsoon current
Page Reference: Page 109
MCQ 18
Ocean waves are mainly generated by:
- A. Earthquakes only
- B. Winds
- C. Volcanic eruptions only
- D. Salinity changes only
Page Reference: Page 110
MCQ 19
Tides are caused mainly by:
- A. Ocean currents only
- B. Gravitational pull of Moon and Sun
- C. Earthquakes only
- D. Volcanoes only
Page Reference: Page 111
MCQ 20
The highest tides are called:
- A. Neap tides
- B. Spring tides
- C. Ebb tides
- D. Drift tides
Page Reference: Page 111
One-Word / Very Short Answer Questions
| Question | Answer | Page Reference |
|---|---|---|
| How much of Earth’s surface is covered by water? | 71% | Page 104 |
| Which is the largest ocean? | Pacific Ocean | Page 104 |
| What is the submerged extension of continent called? | Continental shelf | Page 105 |
| Which feature connects shelf and deep ocean floor? | Continental slope | Page 105 |
| What is the deep ocean floor called? | Abyssal plain | Page 105 |
| Which is the deepest ocean trench? | Mariana Trench | Page 106 |
| In which unit is salinity measured? | Parts per thousand | Page 107 |
| What is average ocean salinity? | 35‰ | Page 107 |
| Which layer separates warm and cold ocean water? | Thermocline | Page 108 |
| What is horizontal movement of ocean water called? | Ocean current | Page 109 |
| Which warm current flows in Atlantic Ocean? | Gulf Stream | Page 109 |
| Which cold current flows near Canada? | Labrador Current | Page 109 |
| What mainly generates ocean waves? | Winds | Page 110 |
| What causes tides? | Gravitational pull of Moon and Sun | Page 111 |
| Which tides are highest? | Spring tides | Page 111 |
| Which tides occur during right-angle position of Moon and Sun? | Neap tides | Page 111 |
| Which giant sea waves are caused by underwater earthquakes? | Tsunami | Page 110 |
| Where are coral reefs mainly found? | Warm shallow tropical waters | Page 106 |
| Which factor increases salinity? | Evaporation | Page 107 |
| Which ocean feature is economically important for fishing? | Continental shelf | Page 105 |
Assertion and Reason Questions
Question 1
Assertion (A): Continental shelves are economically important regions.
Reason (R): Rich fishing grounds and mineral resources are found on continental shelves.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 105
Question 2
Assertion (A): Salinity increases in regions of high evaporation.
Reason (R): Evaporation removes water but leaves salts behind.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 107
Question 3
Assertion (A): Ocean temperature decreases with depth.
Reason (R): Sunlight penetrates only upper layers of ocean water.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 108
Question 4
Assertion (A): Thermocline separates warm and cold ocean water.
Reason (R): Temperature changes rapidly across thermocline zone.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 108
Question 5
Assertion (A): Warm ocean currents increase coastal temperatures.
Reason (R): Warm currents transport heat from equatorial regions.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 109
Question 6
Assertion (A): Cold ocean currents lower temperatures of nearby coasts.
Reason (R): Cold currents originate from higher latitudes.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 109
Question 7
Assertion (A): Ocean waves are mainly generated by winds.
Reason (R): Friction between air and water transfers energy to ocean surface.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 110
Question 8
Assertion (A): Tsunamis are highly destructive ocean waves.
Reason (R): Underwater earthquakes displace large volumes of water suddenly.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 110
Question 9
Assertion (A): Tides are caused by gravitational pull of Moon and Sun.
Reason (R): Gravitational attraction affects ocean water levels on Earth.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 111
Question 10
Assertion (A): Spring tides are higher than neap tides.
Reason (R): Gravitational pull of Sun and Moon acts together during spring tides.
Options:
- A. Both A and R are true and R is the correct explanation
- B. Both A and R are true but R is not the correct explanation
- C. A is true but R is false
- D. A is false but R is true
Page Reference: Page 111
Important Exam-Based Concept Questions
Question 1
Explain the importance of oceans on Earth.
Page Reference: Page 104
Question 2
Describe the major relief features of ocean floor.
Page Reference: Page 105–106
Question 3
Explain the characteristics and importance of continental shelves.
Page Reference: Page 105
Question 4
Discuss the formation and significance of ocean trenches.
Page Reference: Page 106
Question 5
Explain the formation of mid-oceanic ridges.
Page Reference: Page 106
Question 6
Discuss the causes and distribution of ocean salinity.
Page Reference: Page 107
Question 7
Explain the factors affecting ocean temperature.
Page Reference: Page 108
Question 8
Describe the concept and significance of thermocline.
Page Reference: Page 108
Question 9
Explain the causes and characteristics of ocean currents.
Page Reference: Page 109
Question 10
Differentiate between warm and cold ocean currents.
Page Reference: Page 109
Question 11
Discuss the influence of ocean currents on climate.
Page Reference: Page 109
Question 12
Explain the formation and characteristics of ocean waves.
Page Reference: Page 110
Question 13
Describe the causes and effects of tsunamis.
Page Reference: Page 110
Question 14
Explain the causes of tides.
Page Reference: Page 111
Question 15
Differentiate between spring tides and neap tides.
Page Reference: Page 111
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