Give answer to the following questions approximately in 1- 15 words: -
Q 1. Why is the ocean water salty?
Ans. Several mineral salts get dissolved in the ocean water. Due to this the ocean water is salty.
Q 2. Why there is a dense fog near Newfoundland?
Ans. Near the Islands of Newfoundland the warm water of Gulf Stream mixes with the cold water of Labrador. Due to this a dense fog is formed over there.
Q 3. Explain the route of Gulf Stream current.
Ans. The Gulf Stream starts from the Gulf of Mexico and it reaches to the Islands of Newfoundland.
Q 4. Write down the main ocean currents of North Atlantic Ocean cycle.
Ans. 1. The Gulf Stream 2. Canary Current
3. Saragasso Sea
Q 5. What do you understand by Tsunami?
Ans. ‘Tsu’ means coastal and ‘Nami’ means long waves of water. The Tsunami are the long waves of water striking to the coastal areas.
Answer the following questions in approximately 50- 60 words:-
Q 6. What is the difference between Spring Tide and Neap Tide?
Spring Tide During the Spring Tide the sun, the moon and the earth all are in a line. The sun and the moon both pull the ocean water jointly.
The rise of water is maximum.
Neap Tide During the Neap Tide the moon, earth and sun are right angles to that of the moon. The sun pulls water to its side and the moon full towards itself. Due to the nearness of the moon the water rises towards moon only.
The rise of water is lower than as usual.
Q 7. Differentiate between warm water ocean current and cold water ocean current.
Ans. The temperature remains high in Equatorial regions but lower in Polar Regions. The currents going away from the Equator are always warm. Whereas, the currents coming from the poles are always cold.
Q 8. Why are the ocean currents of Indian Ocean not so definite and systematic?
Ans. The winds in the Indian Ocean are seasonal and change their direction. Due to this, the ocean currents also change their direction. This is the reason the ocean currents of Indian Ocean are not so definite and systematic.
Q 9. Tide is very useful for ships. How?
Ans. Due to the tide, the deposits of soil against the mouth of the river, washed away. Thus, the soil do not get deposited on the harbours and ships can sail up to a great distance inside.
Q 10. Why a Spring Tide occurs in full moon and no moon days?
Ans. The sun, the moon and the earth all are in a line during no moon day and full moon day. This is the reason, a spring tide occurs in both these phases.
Q 11. Why does the Gulf Stream affect the climate of Europe?
Ans. 1. Due to the warm water of Gulf Stream the glaciers moving from the poles melt and do not create obstruction to ships after reaching down.
2. The ports of European countries remain open even in winter season due to its warm water.
Q 12. What is the difference between the ocean waves and the ocean currents?
Ocean Waves-The waves arise due to the speed of the wind blowing over the surface of oceans. The water of the oceans always ripples with the winds over the Ocean surface. These are called waves.
Ocean Currents- When the ocean water moves in a particular direction it is called ocean current. The water in the ocean keeps on moving from one place to the other.
Q 13. Write down a case study of a place that is affected by Tsunami.
Ans. On December 26, 2004, a most powerful Tsunami occurred on the coast of Indian Ocean. This brought devastation in 11 countries. More than 2 lakh people were killed and many more were rendered homeless. Tamilnadu, Kerala, Andhra Pradesh and Pondicherry etc. states suffered the most in India.
Please refer to attached file for CBSE Class 7 Social Science Worksheet - Revision Worksheet (1)