The Tunguska Event: NBSE class 9 Alternative English answers

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Get questions, answers, notes, and solutions of the chapter The Tunguska Event which is a part of class 9 Alternative English syllabus for students studying under the Nagaland Board of School Education. However, these notes should be used only for references and additions/modifications should be made as per the requirements.

The Tunguska Event NBSE class 9 Alternative English answers

SUMMARY: The chapter The Tunguska Event by Carl Sagan discusses a peculiar event that happened in the early morning hours of June 30, 1908, in Central Siberia. The particular event was a giant ball of fire that had come down from the sky and supposedly plunged into the surface of the Earth. The explosion was so powerful that it could have been mistaken for a nuclear explosion. However, when scientists and researchers tried to find a crater that could have formed because of the explosion and impact, they could not find anything like that, which was strange.

The chapter tries to explain what might have happened that day and why there is no such crater. The writer gives various accounts of people who have witnessed the phenomenon. But it fails to give a proper explanation of what it could have been. There are only assumptions and theories, but nothing certain.

I. Explain with reference to context.

1. There seems to be only one explanation consistent with all the facts…
Choose the correct answer.
What do the scientists think is the most plausible answer to what happened the night of the Tunguska Event?

Answer: c. A piece of a comet hit the Earth

2. Could a rare but natural event, the impact of a sizable cometary fragment trigger a nuclear war?
a. What is the event that is mentioned here?
b. Why would it trigger a nuclear war?
c. What does Sagan suggest we do in order to prevent a nuclear war?

Answer: (a) The Tunguska event is mentioned here.

(b) Because men may assume the catastrophe as a nuclear strike and try to retaliate, which may take the world on the path of destruction.

(c) Carl Sagan suggests we understand comets, collisions, and catastrophes a little better than we do in order to prevent a nuclear war.

II. Answer these questions briefly.

1. What does Sagan mean when he says, “it’s all a matter of time-scale”, in relation to catastrophe?

Answer: When he says, “It’s all a matter of time scale,” Carl Sagan means that evidence gathered from other planets indicates catastrophes like these certainly happen. It may happen now or later. Something that seems impossible might be inevitable in a million years. It is all a matter of time scale.

2. How does a natural event such as these simulate nuclear explosions?

Answer: Natural events such as these simulate nuclear explosions. When such explosions take place, they not only destroy a large area of land, like a megaton nuclear explosion, but they can also form mushroom clouds and eject dust into the atmosphere, but unlike nuclear explosions, there is no radiation fallout.

III. Answer these questions.

1. What are the three explanations offered for the Tunguska Event? Why are these explanations not plausible?

Answer: The three explanations offered for the Tunguska event are:

I. It was caused by a piece of hurtling antimatter which annihilated on contact with the ordinary matter of the Earth, disappearing in a flash of gamma rays.
II. It was caused by a mini black hole which passed through the earth in Siberia and out the other side.
III. It was a spaceship of some unimaginably advanced extraterrestrial civilisation in desperate mechanical trouble, crashing into a remote region of an obscure planet.

These explanations are not plausible because of the absence of radioactivity at the impact site, the absence of records of atmospheric shock waves showing a hint of an object booming out of the North Atlantic later that day, and the absence of any trace of a spaceship at the site.

2. Describe the cause of the Event.

Answer: The Tunguska event was probably caused by an icy cometary fragment about a hundred metres across, the size of a football field, weighing a million tonnes, moving at about 30 kilometres per second, 70,000 miles per hour.

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