Water Class 7 Social Science Solutions

Class 7 Modern English Solutions All Chapters“Ever wondered why our Earth is called the watery planet? Let’s find out from the chapter “Water Class 7 Social Science“! Learn about freshwater, salty water, the water cycle, ocean salinity, and major oceans. Plus, understand the impact of natural and man-made disasters on water and key disaster management.

Water Class 7 Social Science Notes

Fresh and Saline

Water makes up 71% of the earth’s surface. Therefore our earth is known as a watery planet. Out of the total water available on this earth, about 97.5% is saline. The ocean water is saline but the water in rivers and many lakes is fresh. The Loktak Lake in Manipur is a freshwater lake. Water exists in various forms i.e., water, ice and vapour.

Hydrological Cycle

Water evaporates from the oceans and smaller water bodies and reaches the atmosphere as water vapour. When cooling, this water vapour turns into water droplets and falls to earth as rain. The rainwater runs into the sea from where it gets evaporated. This cycle is known as hydrological cycle or water cycle.

Salinity Of Oceans

Saltiness is called salinity. Sodium Chloride or common salt is the most important salt. The average salinity of the ocean is 35 grams of salt per 1000 grams of water. In areas where evaporation is high, the salinity is high. In polar areas where evaporation is low, the salinity is very low.

Major Water Bodies

There are four major oceans on the earth. They are Pacific Ocean, Atlantic Ocean, Indian Ocean and Arctic Ocean.

• Pacific Ocean- It is the largest and deepest and triangular. It is one-third of the earth’s surface.
• Atlantic Ocean- The Atlantic Ocean is S-shaped and covers one-sixth -of the earth’s surface. It is the busiest ocean providing trade and transport facilities between North America and Europe.
• Indian Ocean- The Indian Ocean is often called half an ocean because it does not open northwards. The deepest part is the Sunda Trench (7400m).
• Arctic Ocean- It is the smallest ocean. It is almost frozen and located around the North Pole.

Disaster

Disaster is a serious disruption, occurring over a relatively short time involving widespread human, material, economic or environmental losses. Owing to its geo-climatic, geological and physical features, Manipur is vulnerable to all major natural hazards.

Disaster can be divided into

l. Natural Disaster and
2. Man-made Disaster.

Natural Disasters include Earthquakes, Landslides, mudflows, volcanic eruptions, floods, droughts, hurricanes, tornadoes, blizzards, tsunamis, cyclones etc.

Man-made Disasters include forest fires, transport accidents, oil spills, nuclear explosions etc.

Disaster Management: Prevention, Preparation, relief and recovery are four essential parts of Disaster management.

Water Class 7 Social Science Questions and Answers

Access the solved questions and answers for the lesson “Water” From your Class 7 BOSEM Social Science Textbook. The Questions and Answers are divided into very short answer types, and short answer types, choose the correct answers and match the following.

Answer the following questions in a sentence.

Q1. Why is Earth known as a watery planet?

Ans: The earth is known as a watery planet because water makes up 71% of the earth’s surface.

Q2. Why Manipur is prone to frequent floods during the rainy season>

Ans: Various factors like high rainfall, orientation of Manipur valley with Manipur river system, artificial dams etc, make Manipur prone to floods during the rainy season.

Q3. What is a disaster?

Ans: A Disaster is a serious disruption, occurring over a relatively short time and involving widespread human, economic or environmental losses.

Answer the following questions in about 100 words each.

Q1. Explain the hydrological cycle or water cycle.

Ans. The movement of water as it evaporates from the oceans and water bodies reaches the atmosphere as water vapour, turns into water droplets, falls on earth as rain, and runs into the sea. “This cycle is called hydrological or water cycle.

2. In what ways are the tides and currents useful to man?

Ans. Tides are useful in fishing. High tides help big ships to enter or leave the harbour safely. The tidal force can be used to generate power.
Currents help in navigation. Ships that follow ocean currents move faster and save fuel. The meeting of warm and cold currents leads to an abundance of fish food and develops into fishing grounds.

(c) Explain disaster management

Ans. The process of organization and management that is implemented before, during or after any type of catastrophic event takes place is disaster management. The management of natural hazards involves disaster research and predictions of the history of the prone area. Prevention, preparation, relief and recovery are four essential parts of disaster management.

Choose the correct answer

I. The salinity of the ocean is high in the area of
a) Low evaporation
b) High evaporation
c) High Humidity
d) Heavy Rainfall

Ans: High Evaporation

ii. Natural Disaster is caused by
a) Road accident
b) Nuclear explosion
c) Deforestation
d) Earthquake

Ans: Earthquake

iii. The Deepest part of the ocean is found in
a) Atlantic Ocean
b)Indian Ocean
c) Bay of Bengal
d) Pacific Ocean

Ans: Pacific Ocean

Match the two-column

Ans:

Also Read: Lesson 3 Air