7th class subject geography chapter 3 tides quetions and answers
Answers
Answer:
mention questions....... however below may help you
Explanation:
Tides
The rhythmic rise and fall of water twice in a day is called a tide.
High Tide: This occurs when water covers much of the shore by rising to its highest level.
Low Tide: There is a low tide when water falls to its lowest level and recedes from the shore.
Tides are caused by the strong gravitational pull exerted by the sun and the moon on the earth’s surface. The rise and fall of water due to tides is used for generating electricity in some places. The water of the earth closer to the moon gets pulled under the moon’s gravitational force and causes a high tide.
Types of Tides
spring tide
Spring Tides: During the full moon and new moon days, the sun, the earth and the moon are in the same line and the tides are the highest. These tides are called spring tides.
neap tide
Neap Tide: When the moon is in its first and third quarters, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of the sun and the earth. This results in low tides; called neap tides.
Advantages of High Tide:
They help in navigation. They raise the water level close to the shores and help the ships to arrive at the harbor more easily.
They help in fishing. More fish come closer to the shore during high tides. This helps the fishermen to have a good catch and earn more.
Ocean Current
They are streams of water flowing continuously on the ocean’s surface in definite directions. They influence the temperature conditions of the area. They may be warm or cold.
Warm Current: They originate near the equator and move towards the poles. The Gulf Stream is a warm current. They bring warm temperature over land surface.
Cold Current: They carry water from polar or higher latitudes to tropical or lower latitudes. For example; the Labrador Ocean Current. They result in cold temperature over the land surface.
Effect of the meeting of warm and cold currents:
They provide the best fishing grounds of the world. Some example of these are: Seas around Japan and Seas around the eastern coast of North America.
They lead to foggy weather which makes navigation difficult.
Answer:
NCERT Solutions For Class 7 Geography Social Science Chapter 5 Water
Q. 1. Answer the following questions briefly.
(a) What is precipitation?
(b) What is water cycle?
(c) What are the factors affecting the height of the waves?
(d) Which factors affect the movement of ocean water?
(e) What are tides and how are they caused?
(f) What are ocean currents?
Ans. (a) Falling of moisture in the form of rainfall, snow, fog, sleet and hailstone is termed as precipitation.
(b) The water cycle is the process by which water continually changes its form and circulates between oceans, atmosphere and land.
(c) Winds, earthquakes, volcanic eruption or under water landslides are the factors affecting the height of the waves. The stronger the wind blows, the bigger the wave becomes.
(d) Temperature, winds, gravitational pull of the sun, the earth and the moon; warm and cold currents are the factors that affect the movement of ocean water.
(e) Tides are the rhythmic rise and fall of ocean water that occur twice in a day. The strong gravitational pull exerted by the sun and the moon on the earth’s surface causes the tides.
(f) Ocean currents are streams of water flowing constantly on the ocean surface in definite directions.
Q. 2. Give reasons:
(a) Ocean water is salty.
(b) The quality of water is deteriorating.
Ans. (a) The water of the oceans is salty as it contains large amount of dissolved salts.
(b) Water is being used injudiciously. Whatever potable water is available, its quality is not good. It is because industrial effluents and untreated water of industries get mixed into streams and rivers. Swerage water also gets mixed into these water bodies. As a result, the quality of water is deteriorating day by day.
Q. 3. Tick the correct answer.
(a) The process by which water continually changes its form and circulates between oceans, atmosphere and land
(i) Water cycle (ii) Tides (iii) Ocean currents.
(b) Generally the warm ocean currents originate near
(i) Poles (ii) Equator (iii) None of these.
(c) The rhythmic rise and fall of ocean water twice in a day is called
(i) Tide (ii) Ocean current (iii) Wave
Ans. (a)—(i), (b)—(ii), (c)—(i)
ncert-solutions-for-class-7-geography-social-science-chapter-5-water
Q. 5. For Fun
Be a Detective
1. The name of one river is hidden in each of the sentences below. Spot it. Example: Mandira, Vijayalakshmi and Surinder are my best friends
Ans. Ravi
(a) The snake charmer’s bustee, stables where horses are housed, and the piles of wood, all caught fire accidentally. (Hint: Another name for River Brahmputra)
(b) The conference manager put pad, material for reading and a pencil for each participant. (Hint: A distributary on the Ganga-Brahmputra delta)
(c) Either jealousy or anger cause a person’s fall (Hint: Name of a juicy fruit!)
(d) Bhavani germinated the seeds in a pot (Hint: Look for her in West Africa)
(e) “I am a zonal champion now” declared the excited athlete. (Hint: The river that has the biggest basin in the world)
(f) The tiffin box rolled down and all the food fell in dusty potholes. (Hint: Rises in India and journeys through Pakistan)
(g) Malini leaned against the pole when she felt that she was going to faint. (Hint: Her delta in Egypt is famous)
(h) Samantha mesmerised everybody with her magic tricks. (Hint: London is situated on her estuaiy)
(i) “In this neighbourhood, please don’t yell! Owners of these houses like to have peace. Warned my father when we moved into our new flat”. (Hint: colour!)
(j) ‘Write the following words’, Marc! “On”, “go”, “in”……….. said the teacher to the
little boy in KG Class. (Hint: Rhymes with ‘bongo’)
Now make some more on your own and ask your classmates to spot the hidden name. You can do this with any name: that of a lake, mountains, trees, fruits, school items etc.
TAns. eesta, (b) Padma, (c) Orange, (d) Niger, (e) Amazon, (f) Indus, (g) Nile,
(h) Thames, (i) yellow,(j) Conga.
Carry on Detective
2. With the help of an atlas, draw each river which you discovered in For fun (0, on
an outline map of the world.
Ans. Do yourself.
VERY SHORT ANSWER TYPE QUESTIONS
Q.1. What is terrarium?
Ans. It is an artificial enclosure for keeping small house plants. .
Q.2. Which type of water do the ocean bodies and the seas contain?
Ans. They contain salty water.
Q.3. What do you mean by salinity? [V. Imp.]
Ans. Salinity is the amount of salt in grams present in 1000 grams of water.
Q.4. What is the average salinity of the oceans?
Ans. The average salinity of the oceans is 35 parts per thousand.
Q.5. What is the salinity of Dead sea?
Ans. The salinity of Dead sea is 45 parts per thousand.