Water Class 7 Worksheet Geography Chapter 5

Q1. What is a terrarium?

Ans: A terrarium is an artificial enclosure designed for keeping small house plants. It provides a controlled environment that helps plants thrive.

• Typically made of glass or clear plastic.
• Allows for light and moisture retention.
• Creates a mini ecosystem that can be self-sustaining.

Q2. What is the effect of high tide?

Ans: High tide occurs when the water level rises to its highest point, covering much of the shore. This phenomenon is part of the natural cycle of tides, which includes:

• High tide: Water reaches its peak level.
• Low tide: Water recedes to its lowest level.

High tides have several important effects:

• They facilitate navigation by raising water levels near the shore, making it easier for ships to enter harbours.
• They enhance fishing opportunities, as many fish are drawn closer to the shore during high tides.
• They can be harnessed for electricity generation in some regions.

Q3. What is the first indication of a tsunami?

Ans: The first indication that a tsunami is approaching is the rapid withdrawal of water from the coastal region, which is often followed by a destructive wave. Key points to note:

• The water recedes quickly, exposing the sea floor.
• This phenomenon can be misleading, as many people may gather at the coast to observe the unusual sight.
• Unfortunately, this curiosity can lead to significant casualties when the tsunami strikes.

Q4. Where does the word tsunami come from and what does it mean?

Ans: Tsunami is a Japanese term that translates to “harbour waves”. This name reflects the significant destruction these waves can cause to harbours. Key points about tsunamis:

• Tsunamis are often triggered by underwater events such as earthquakes, volcanic eruptions, or landslides.
• They can reach heights of up to 15 metres and travel at speeds exceeding 700 km/h.
• The largest recorded tsunami was 150 metres high.
• The 2004 tsunami caused widespread devastation along the coasts of India.

Q5. What is water cycle?

Ans: The water cycle is the continuous process through which water changes its form and circulates between the oceans, atmosphere, and land. It involves several key stages:

• Evaporation: Water from oceans and other bodies turns into vapour due to heat from the sun.
• Condensation: The water vapour cools and forms clouds.
• Precipitation: Water falls back to the earth as rain, snow, or sleet.
• Runoff: Water flows over the land, returning to oceans and rivers.

Q6. What are the factors affecting the height of the waves?

Ans: Factors affecting the height of the waves:

• Storms: High-speed winds during storms create large waves.
• Earthquakes: Seismic activity can displace vast amounts of ocean water.
• Volcanic eruptions: Underwater eruptions can also generate significant waves.
• Underwater landslides: These can shift water and lead to large waves.
• Tsunamis: Result from sudden ocean floor movements, potentially reaching heights of 15m or more.

The largest recorded tsunami was 150m high and can travel over 700 km/h.

Q7. What are the major movements of ocean water?

Ans: The movements of ocean water can be classified into three main categories:

Waves: Waves are created when the surface of the ocean rises and falls due to wind. The stronger the wind, the larger the waves become.

Tides: Tides are the regular rise and fall of ocean water, occurring twice daily.

• High tide: Water reaches its highest level, covering much of the shore.
• Low tide: Water recedes to its lowest level, exposing more of the shore.

Ocean Currents: These are continuous streams of water flowing in specific directions across the ocean's surface.

• Warm currents typically originate near the equator and move towards the poles.
• Cold currents transport water from polar regions to warmer areas.

Examples include the Labrador Current (cold) and the Gulf Stream (warm).

Q8. Why are tides important to us?
Ans: Tides are important for several reasons:

• Navigation: High tides raise water levels near the shore, making it easier for ships to enter harbours.
• Fishing: Many fish come closer to the shore during high tides, providing fishermen with a better catch.
• Energy Generation: The rise and fall of tides are harnessed to produce electricity in some regions.

Q9. What are tides and how are they caused?

Ans: Tides refer to the rhythmic rise and fall of ocean water that occurs twice daily. They are influenced by:

• The gravitational pull of the sun and the moon on the Earth's surface.
• High tide 
• Low tide

 During full and new moons, the sun, moon, and Earth align, resulting in the highest tides known as spring tides. Conversely, during the moon's first and last quarters, the gravitational pull from the sun and moon acts in opposite directions, leading to lower tides called neap tides.

Q10. What is precipitation?

Ans: Precipitation refers to any form of water that falls from the atmosphere to the Earth's surface. This includes:

• Rain - liquid water droplets.
• Snow - frozen water crystals.
• Sleet - small ice pellets.

Precipitation occurs when water vapour in the atmosphere cools and condenses, forming clouds. Eventually, this water falls to the ground, replenishing our water sourceslike rivers and lakes.

Q11. What is Tsunami?

Ans: Tsunami refers to a series of massive waves caused by disturbances beneath the sea, such as:

• Earthquakes
• Volcanic eruptions
• Underwater landslides

Key points about tsunamis: 

• They can reach heights of up to 15 metres, with the largest recorded at 150 metres.
• Tsunamis travel at speeds exceeding 700 km/h.
• The 2004 tsunami caused widespread destruction in coastal areas, particularly in India.
  

Q12. What are the major sources of freshwater?

Ans: The major sources of freshwater include:

• Rivers
• Ponds
• Springs
• Glaciers

Q13. Why is the ocean salty?

Ans: The ocean is salty because it contains a large amount of dissolved salts. Here are some key points:

• Most of the salt is sodium chloride, which is common table salt.
• The average salinity of the oceans is about 35 parts per thousand.
• Salinity varies in different bodies of water; for example, the Dead Sea has a salinity of 340 grams per litre.

This high salt content affects the density of ocean water, allowing swimmers to float more easily in areas like the Dead Sea.

Q14. What are spring and neap tides?

Ans: The gravitational pull of the moon affects ocean tides. Here’s how they work:

• High Tides: When the water closest to the moon is pulled, it creates high tides.
• Spring Tides: Occur during the full moon and new moon, when the sun, moon, and earth align, resulting in the highest tides.
• Low Tides: Happen when the moon is in its first and last quarter. The gravitational pull from the sun and moon draws water in opposite directions.
• Neap Tides: These are the lower tides that occur during the moon's first and last quarters.

Q15. Write a short note on Tsunami?

Ans: Tsunami

• Tsunami is a Japanese word that means “Harbour waves” as the harbours get destroyed whenever there is tsunami.
• An earthquake, a volcanic eruption or underwater landslides can shift large amounts of ocean water.
• As a result a huge tidal wave called tsunami, that may be as high as 15m., is formed. The largest tsunami ever measured was 150m. high. These waves travel at a speed of more than 700 km. per hour.
• The tsunami of 2004 caused wide spread damage in the coastal areas of India. The Indira point in the Andaman and Nicobar islands got submerged after the tsunami.