RBSE Solutions for Class 8 Science Chapter 15 Natural Phenomena

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RBSE Solutions for Class 8 Science Chapter 15 Natural Phenomena are part of RBSE Solutions for Class 8 Science. Here we have given RBSE Rajasthan Board Solutions for Class 8 Science Chapter 15 Natural Phenomena.

Rajasthan Board Solutions for Class 8 Science Chapter 15 Natural Phenomena

Board RBSE
Class Class 8
Subject Science
Chapter Chapter 15
Chapter Name Natural Phenomena
Number of Questions Solved 36
Category RBSE Solutions

Natural Phenomena Textbook Questions Solved

I. Multiple Choice Questions

Question 1.

  1. With the increase in velocity of air, air pressure:
    (a) Increases
    (b) Decreases
    (c) No change
    (d) Become double
  2. What will happen if air blows in between two balloons hanged on wooden stick separated by 10 cm distance:
    (a) Balloons come near to each other
    (b) Balloons goes away from each other
    (c) Balloons burst
    (d) No change
  3. Centre of cyclone in a calm area is called:
    (a) Center
    (b) Eye
    (c) Head
    (d) Tail

Answers:

  1. (b)
  2. (a)
  3. (b)

Question 2.
Fill in the blanks

  1. Tornado is dark coloured and funnel type…………….
  2. The air flows from…………….pressure area to pressure area.
  3. Breeze produces due to…………….heating of earth.
  4. Air in motion is called…………….

Answers:

  1. clouds
  2. high, low
  3. uneven
  4. wind

Natural Phenomena Short Answer Type Questions

Question 1.
How does cyclones formed?
Answer:
Water converts into vapour in atmosphere after taking heat. When this vapour condenses and again convert into water droplets. Heat is released in the atmosphere, it makes the surrounding air hot. This hot air rises up, resulting decrease in air pressure, to take place of hot air more speedy air started moving towards the direction of hot air. This cycle is repeated many times, this repetition stops when a low air pressure area is evolved. Around this area many layer of air starts moving in spiral form such condition of weather is called cyclone. Its centre is calm and called eye of the cyclone.

Question 2.
What type of planning is needed to overcome the cyclone?
Answer:
Measures at social and government level:

  1. Forecasting of cyclone by the meteorological department of government.
  2. Speedy communication system to give warning to the fishermen, steamers, government institutions, people living in the coastal regions.
  3. Speedy rescue operation system to shift people at safe places.

Activities done by people:

  1. We should not ignore governmental warnings transmitted on television, radio, newspapers, meteorological department etc.
  2. We should do arrangement of shifting essential domestic goods, domestic animals and vehicles at safer places.
  3. Avoid driving on roads submerged under water.
  4. We should keep the list of telephone numbers of emergency services like police, fire brigade, hospitals, health centres with us.

People living in cyclone prone areas should keep following precautions:

  1. Store of drinking water in adverse situation.
  2. Don’t touch broken electricity wires, wet electric switches.
  3. Give co-operation and help to neighbours and friends as far as possible.

Question 3.
Describe an activity to explain air pressure.
Answer:
Take a plastic bottle, fill it half with hot water, empty it, and immediately close lid/ cap tightly. Pour cold water on bottle on observation it is seen that bottle sticks. Why is this happen? It is so because some water vapour inside the bottle cools and converts into water. It results that inner air pressure of bottle decreases compared to outer air pressure. Due to differences in air pressure bottle sticks. Flying of kite, bursting of balloon, hosting of flag, blowing of dust, rustling of leaves etc occur due to air pressure. All these activities proves that air exerts pressure.

Question 4.
What are the safety measures against the lightning thunder?
Answer:
Measures to protect from thunder lightning:

  1. Don’t stay in open, go inside a building.
  2. Don’t come out of the houses.
  3. Don’t do any activity like washing clothes, bathing etc.
  4. Take shelter in cars or buses.
  5. Don’t stand under tall and single trees.
  6. Don’t lay down in open land.

Natural Phenomena Long Answer Type Questions

Question 1.
What are the reasons of lightning thunder?
Answer:
When temperature rises, then hot air rises upward, it takes water vapour along it. Due to low temperature water vapour condenses in the form of water. Droplets of water comes down with great speed, due to interaction between air and water droplets lightning occurs it creates sound. It is called thunder lightning.

Question 2.
Explain the reasons of flow of air.
Answer:
Earth is not heated uniformly. Parts near the equator get more heat of the sun. Hence air’of surrounding becomes hot. It rises upwards to take their place. Cool breeze from polar region blows towards equator. Due to inequality of hotness air blows from colder to hotter regions. Land becomes hotter than water. In summers land becomes hot. Temperature of surface of the earth is more than oceanic water. The hot air surrounding the earth rises up and cool sea breeze. It starts blowing towards land. They are called monsoon winds also. Speedy air is wind or moving air is called breeze.

Natural Phenomena Additional Questions Solved

I. Multiple Choice Questions

Question 1.
Natural phenomena is
(a) Cyclones
(b) Thunderstorm
(c) Lightning
(d) All of the above

Question 2.
Tornado affected area in INDIA is
(a) Western Ghat
(b) Eastern Ghat
(c) Northern Ghat
(d) Southern Ghat

Question 3.
When warm air rises in upward direction, then
(a) Air pressure decreases
(b) Air pressure increases .
(c) Air pressure remains unchanged
(d) None of the above

Question 4.
Lightning occurs due to:
(a) electricity discharge
(b) rain
(c) wind
(d) None of these

Question 5.
Lightning conductor
(a) destroys the building
(b) protects the building
(c) No effect
(d) none

Question 6.
The material used for lightning rods is:
(a) Copper
(b) Sand paper
(c) Plastic
(d) Bakelite

Question 7.
A thunderstorm is accompanied by:
(a) Tornado
(b) Cyclone
(c) Lightning
(d) All of the above

Question 8.
Development and movement of cyclones are studied by the-
(a) Indian Postal Department
(b) Indian Forensic Department
(c) Indian Meterological Department
(d) Central Investigation Department

Answers:
1. (d)
2. (b)
3. (a)
4. (a)
5. (b)
6. (a)
7. (c)
8. (c)

Natural Phenomena Very Short Answer Type Questions

Question 1.
Define breeze.
Answer:
Moving air is called breeze.

Question 2.
Write the relation between velocity of air and air pressure?
Answer:
When air velocity increases, air pressure reduces.

Question 3.
Which ghat of India is sensitive for cyclones?
Answer:
Eastern ghats of India is sensitive for cyclones.

Question 4.
What is tornado called in USA and Japan?
Answer:
Tornado is called hurricane in America (USA) and typhoon in Japan.

Question 5.
Give the main reason of air current flow.
Answer:
The main reason for air current flow is the non uniform heating pattern at equatorial and polar regions.

Question 6.
What is tornado?
Answer:
Tornado is dark coloured and funnel type clouds and seem as coming from sky towards the earth.

Question 7.
How does monsoon winds caused?
Answer:
Monsoon winds are caused by uneven heating of land and sea.

Question 8.
How does cyclone accompained?
Answer:
Cyclones are accompanied by heavy rainfall and huge sea waves and often disastrous.

Question 9.
What is eye of cyclone?
Answer:
Calm conditions prevail at the centre of the cyclone is called the eye cyclone.

Question 10.
What does cyclone consist of?
Answer:
A cyclone consists of a low pressure area with higher pressure all around. High speed winds circulate violently around the low pressure area.

Natural Phenomena Short Answer Type Questions

Question 1.
Make a list of four incidences which are related to air pressure.
Answer:

  1. Kites flying
  2. Flag waving
  3. Flying of leaves and soil particles
  4. Overfilled balloons bursts

Question 2.
What is lightning conductor ?How does it protect building from lightning?
Answer:
Lightning conductor is a device used to protect building from the effect of lightning. A metallic rod taller than building is installed in the walls of the building during its construction. One end of the rod is kept out in the air and the other end is buried deep inside the ground. The rod provides easy route for transfer of electricity charge to the ground. .

Question 3.
Why is it difficult to insert paper ball in bottle by blow of air?
Answer:
When we blow off air, velocity of air increases at mouth of bottle and air pressure decreases. Air pressure inside the bottle is more than the air pressure at mouth. The air inside the bottle pushes the ball outside that’s why it is difficult to insert the ball in bottle.

Question 4.
Write a short note on tornado.
Answer:
A tornado is a violent spinning column of air appearing like a cloud in the shape of an ice-cream cup or cone. Tornadoes are one of the most deadly and fascinating forces of nature. They can also be described as a towering black funnel extending downward from the base of a large cloud. Tornadoes usually as part of a severe thunderstorm and are also called twisters. Unlike cyclones which occur over tropical ovens, i.e. hot and humid tropical areas. Tornadoes are usually formed over land. They are formed when there is warm, moist air near the ground and cold, dry air above it.

The warm and moist air on being heated by the sun, rises up. On rising, it cools and forms large clouds. To take the place of rising air, more and more surrounding air gets sucked into the bottom of the tornado. It also sucks everything like trees, cars, houses, debris, etc., that comes near its base as it moves over an area. A tornado is smaller than a cyclone but it has high speed winds measuring upto 500 km/h. Hence, it can also cause very heavy destruction.

Question 5.
Explain the safety measures at government or social level?
Answer:
Safety measures at government or social level:

  1. Forecasts and warning about the cyclone are issued by meteorological department.
  2. Rapid communication facilities to provide information promptly and in time to the fisherman, water boats, government agencies, sea shores and public etc.
  3. Rapid transportation to relocate the people in safe place.

Question 6.
What work should be done by the public for safety?
Answer:

  1. We should not ignore the warnings issued by the meteorological department on radio, television, or public newspapers, etc.
  2. We should manage to relocate the essential house items, domestic animals, vehicles, etc into safe zone.
  3. To avoid riding the vehicle of flooded road.
  4. We should keep the telephone numbers of emergency services like police, fire brigade, hospital etc.

Natural Phenomena Long Answer Type Questions

Question 1.
Discuss the formation and path of a cyclone. Draw a labelled diagram of cyclone.
Answer:
Cyclones are huge, very powerful storms. They can be hundreds of kilometers wide. They form only in warm, wet conditions, usually over the sea in tropical areas near the equator. The sequence of events that lead to the formation of cyclone is as follows:

    1. When water from the sea evaporates, it takes up heat from the atmosphere to change into water vapour.
    2. Air over the sea gets heated by the sun. As the warm air rises, it is located with moisture from the sea.
    3. As this air gets heated, it becomes lighter and rises up further, causing a low pressure region to develop. More air rushes in towards the center of the low pressure region.
    4. This process continues and results in a very low pressure region in the center with very high speed winds revolving around it. The swirling winds rotate faster and faster, forming a huge circle which can be upto 200 km across.
      RBSE Solutions for Class 8 Science Chapter 15 Natural Phenomena 1

This is the weather condition that we can call a cyclone. Thus the cyclone consists of a low pressure area with higher pressure all around. The winds tend to blow’ towards the low pressure region and circulate violently around the center with great speed.

Question 2.
Explain the wind currents due to uneven heating of land and water.
Answer:
Land and sea winds blow because the land heats up more during the day but cools down faster at night. During summer, land over India becomes warmer than the sea around it. This causes the winds to blow from the sea into land. These winds come from the south west direction and bring moisture with them from the Indian Ocean. They bring rain to almost all parts of India. In winters, the direction of the winds is reverse, and they flow from land to sea hence they carry a little moisture and so cause small amount of rain in winter Only a part of these winter winds which flows from eastern India over the Bay of Bengal is able to absorb moisture from the Bay and bring rain, to western region of southern India. These winds are known as monsoon winds.

Question 3.
Mention the ill effects of cyclone that occurred in Odisha in 2013.
Answer:
At 9:00 pm on 12th October 2013 rotating winds collide at sea coast of Odisha with the speed of 220 km/hr with heavy rain. High water waves arise in the sea. Sea water enter in the coastal area. These strong winds and water heavily damage houses and lacks of hectare of agricultural land flooded with water, crops were destroyed, electric poles were uprooted. There were darkness everywhere, many people loss their lives. This natural phenomenon is called as Cyclone. In American continent it is called as ‘Hurricane’ and in Japan as Typhoon’.

Question 4.
Explain how lightning occurs in Thunderstorm.
Answer:
Lightning is an electrical discharge that moves through the clouds in a thunderstorm. A thundercloud in the sky has many frozen droplets of water in the form of small pieces of ice. When wind blows, the frozen droplets collide with each other and become electrically charged by friction. This give rise to a whole cloud filled up with electrical charges. In general the positive charges form at the top of the cloud and the negative charges form near the lower edges of the cloud.

A positive charge area builds up below the cloud on the ground due to friction with wind and rain, and there is accumulation of positive charges near the ground and on tree tops. The attraction between the charges may be great enough to cause electrons to jump the air gap between the objects. Once the few electrons start across the gap, they heat up the air such that more and more electrons jump across the gap. This heats the air even more. It all happens very fast, and the air gets so hot that it glows for a short time. This cause a spark and we see it as lightning.

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