Oceans and Life — Class 9 MCQs with Answers
Class 9 CBSE Social Science · Chapter 10
78 practice questions · 25 Easy · 28 Medium · 25 Hard · Updated
Jump to the 6 solved questions
Practise the most important Class 9 CBSE Social Science questions from Chapter 10, "Oceans and Life". You get 10 timed quizzes made from 78 NCERT-based MCQs, with answers and explanations. The questions are split into 25 Easy, 28 Medium and 25 Hard. Warm up on the basics, then move on to the exam-level questions that top scorers in CBSE Board exams get right.
To score well in "Oceans and Life", focus on dates, cause and effect, and reading maps and sources. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This helps you stay accurate when time is short, just as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Oceans and Life, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 9 Social Science mastery score. Try the 6 sample questions below: tap an option to see the answer and a worked explanation. Sign in free to start practising.
Oceans and Life — important questions & MCQs with answers (Class 9 Social Science)
6 solved questions from this chapter's difficulty levels, each with its answer and explanation. Tap an option to check yourself.
0 of 6 answered
- Q1 of 6Easy
What is salinity of ocean water usually measured as?
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Answer: Grams of salt dissolved in 1,000 grams of water
Explanation: Salinity is the amount of dissolved salts, expressed as grams of salt per 1,000 grams (parts per thousand) of sea water.
- Q2 of 6Easy
The rhythmic rise and fall of sea level twice a day is called:
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Answer: Tides
Explanation: Tides are the regular rise and fall of sea water, usually occurring twice a day.
- Q3 of 6Medium
Which activity is the BEST example of the blue economy working in a sustainable way?
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Answer: Generating tidal energy while protecting marine life
Explanation: The blue economy uses ocean resources for growth without harming ecosystems; clean tidal energy that protects marine life fits this idea.
- Q4 of 6Medium
Assertion (A): The 2004 Indian Ocean tsunami led many countries to set up effective tsunami early warning systems. Reason (R): Cyclones in the North Indian Ocean are named from a list of names submitted by 13 member countries.
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Answer: Both A and R are true but R is not the correct explanation of A
Explanation: Both are true. A happened because of the huge scale of the 2004 disaster, while R is about how cyclones are named, so R does not explain A.
- Q5 of 6Hard
Two open-ocean stations at the same latitude record different surface salinities: Station X is 32 ppt and Station Y is 37 ppt. Which single difference best explains the higher salinity at Station Y?
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Answer: Station Y lies in a hot, dry zone with strong evaporation and little fresh-water inflow
Explanation: Strong evaporation removes water while leaving salts behind, and little fresh-water inflow means the salts are not diluted, so Station Y is saltier.
- Q6 of 6Hard
Assertion (A): The Moon influences tides more than the Sun. Reason (R): The Sun is much smaller than the Moon.
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Answer: A is true but R is false
Explanation: A is true the Moon's tidal effect is greater but R is false the Sun is far larger than the Moon. The Moon's stronger tidal effect comes from its much closer distance, not from its size.
Oceans and Life notes: key concepts (Class 9 Social Science)
Oceans cover most of the planet, store its heat and support an enormous range of life. This chapter covers the properties and movements of ocean water, the resources oceans provide, and how coastal communities prepare for the disasters the sea can bring.
| Movement | Caused by | What moves |
|---|---|---|
| Waves | Wind blowing over the water | Energy travels forward; the water mostly moves up and down |
| Tides | Gravitational pull of the Moon and the Sun | Sea level rises and falls, usually twice a day |
| Currents | Winds, and differences in temperature and salinity | Large masses of water flow in a definite direction |
| Spring tide | Neap tide | |
|---|---|---|
| Sun, Moon and Earth | In a straight line | Sun and Moon at right angles to the Earth |
| Their pulls | Combine | Partly cancel each other |
| When | New moon or full moon | First and last quarters of the Moon |
| Tides | Highest; very high highs and very low lows | Lowest, weakest tides |
| Condition | Salinity | Example |
|---|---|---|
| Ocean average | About 35 parts per thousand | 35 g of salt in 1,000 g of sea water |
| High evaporation, little outflow | Higher | Dead Sea |
| Hot, dry zone, little fresh-water inflow | Higher | Drier sub-tropical belts |
| Large river inflow | Lower | Where the Ganga empties into the sea |
| Heavy rainfall | Lower | The equator, despite its heat |
- 1Detect the hazard
- 2Analyse the data
- 3Send a timely alert
- 4People respond and evacuate, moving to higher ground away from the coast
- Extent of the oceans
- Oceans cover about 71% of the earth's surface and hold most of its water, which is why the planet looks blue from space.
- Salinity
- The quantity of dissolved salts in seawater, averaging about 35 parts per thousand and varying with evaporation, rainfall and river inflow.
- Ocean temperature
- Surface water is warmest near the equator and cools towards the poles, and temperature also falls with depth.
- Waves
- Undulations of the sea surface produced by wind; the water itself largely moves up and down while the energy travels forward.
- Tides
- The regular rise and fall of sea level caused by the gravitational pull of the moon and sun, giving high and low tides twice daily in most places.
- Spring and neap tides
- Spring tides are the highest, when sun, moon and earth align; neap tides are the lowest, when the sun and moon pull at right angles.
- Ocean currents
- Large-scale movements of water driven by winds and by differences in temperature and salinity, carrying heat around the globe.
- Warm and cold currents
- Warm currents move from the equator polewards and cold currents in the reverse direction; where they meet, fishing grounds are rich.
- Currents and climate
- Currents moderate coastal climates, keeping some high-latitude coasts ice-free and making some tropical coasts cooler than expected.
- Marine life and ecosystems
- Oceans support life from plankton to whales, with coral reefs and estuaries among the most productive and most fragile habitats.
- Ocean resources
- Fisheries, salt, oil and gas, minerals, tidal and wave energy, and the shipping routes that carry most world trade.
- Threats to the oceans
- Overfishing, oil spills, plastic and chemical pollution, warming and acidification, all of which damage marine ecosystems.
- Ocean-related disasters
- Cyclones, storm surges and tsunamis strike coasts with little warning, and low-lying areas are the most exposed.
- Disaster preparedness
- Early-warning systems, evacuation drills, cyclone shelters, mangrove belts and building rules together reduce loss of life and property.
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Oceans and Life — FAQs
What are the key concepts in Class 9 Social Science Oceans and Life?+
Oceans cover most of the planet, store its heat and support an enormous range of life. This chapter covers the properties and movements of ocean water, the resources oceans provide, and how coastal communities prepare for the disasters the sea can bring. Key ideas include Extent of the oceans, Salinity, Ocean temperature, Waves, Tides, Spring and neap tides.
What does Class 9 Social Science Chapter 10 (Oceans and Life) cover on XamBaaz?+
It has 78 NCERT-based MCQs on "Oceans and Life": 25 Easy, 28 Medium and 25 Hard. Together they make 10 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE Board exams.
Are these "Oceans and Life" questions free to practise?+
Yes. Sign in with Google to practise "Oceans and Life" free. Full unlimited access is ₹999/year. One year from the day you pay. You stay in Class 9 till 31 March; on 1 April your account moves up to Class 10 and the rest of your year carries over. No chapter is charged separately.
How should I revise "Oceans and Life" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 10 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Oceans and Life" MCQs available with answers?+
Yes. 6 sample questions are on this page with answers: tap an option, or "Show answer", to see the correct option and a step-by-step explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Oceans and Life" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Oceans and Life (Class 9 Social Science)?+
The questions that matter most test Extent of the oceans, Salinity, Ocean temperature, Waves, Tides, Spring and neap tides. This page shows 6 solved important MCQs with answers and explanations. Sign in to practise all 78 questions on the chapter as timed quizzes.
Is there an online quiz for Oceans and Life?+
Yes — Class 9 Social Science Oceans and Life has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.
Are there question answers and extra questions for Oceans and Life (Class 9 Social Science)?+
Yes. This page has 6 solved questions on Oceans and Life, each with the correct answer and a short explanation. Sign in to practise all 78 questions on the chapter as timed quizzes.
Are there assertion–reason questions for Oceans and Life (Class 9 Social Science)?+
Yes. The Oceans and Life question bank has 5 assertion–reason questions in the CBSE board format, alongside the regular MCQs. Each comes with the answer and a worked explanation. Sign in to practise them in timed quizzes.