National Science Olympiad Forum By SOF Olympiad Trainer - Page 57

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Subject :NSO    Class : Class 7

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Subject :NSO    Class : Class 6

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Subject :NSO    Class : Class 6

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Subject :NSO    Class : Class 5

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Subject :NSO    Class : Class 2

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Subject :NSO    Class : Class 4

Ans 1:

Class : Class 5
Can you tell me the answer for this question. I marked A , but the answer is B.

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Subject :NSO    Class : Class 4

Ans 1:

Class : Class 4
Please give the solution for the above mentioned question •

Ans 2:

Class : Class 4
Why is the solution not there? Please give as I want to know how that is the correct answer.

Ans 3:

Class : Class 4
The answer is option A.

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Subject :NSO    Class : Class 4

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Subject :NSO    Class : Class 5

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Subject :NSO    Class : Class 5

Ans 1:

Class : Class 5
how can we cover fire with lid

Ans 2:

Class : Class 5
That is the question! Practical ans. - Water over fire

Ans 3:

Class : Class 5
I will show you why it should be none of them.If we pour water on the fire, the fire may die down a little, but the oil can float on the water due to is lesser density compared to H2O and therefore, can still catch fire. For option B, it depends on the type of lid. if we have a lid that is a conductor of heat, it will become a permanent 'NO TOUCH OR GO CLOSE TO' zone; if the handle of the lid is a conductor of heat, it will be hard to remove or move it to another place. And BTW, the theory that says that a fire cannot survive without O2 wont work here as the lid will have tiny gaps through which air and O2 can go through. For option C, it will definitely not work if we blow air from our mouth, but there is an exception for a fire extinguisher. For option D, the fire releases CO (Carbon monoxide) and other harmful gases into the air. So, it would be better to open the windows to let the gases go outside. Option D is the best of them all, but I said none as the problem can literally be solved by silicon dioxide (silica or sand, take your pick). We all know that sand can extinguish fires and the oil is less prone to reignite as sand is a bad conductor of heat.

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