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Subject :NSO    Class : Class 7

A thermo flask is a household item that is used to keep things warm or cold for a long time. What is the use of silvered wall in thermo flask?


A To reduce the flow of heat by conduction.
B To increase the temperature by convection.
C To reflect the heat back to reduce radiation.
D To prevent the glass vessel from breaking.


Ans 1:

Class : Class 7
A

Ans 2:

Class : Class 8
option c

Ans 3:

Class : Class 7
In my opinoin A is corrcect beacuse silvered wall is a solid thing and solid thing get's heat through the process of conduction.

Ans 4:

Class : Class 7
Option C is the correct answer as the silvered walls of the thermo flask helps the liquid to sustain its form by reflecting the heat by Radiation (Heat that does not need any medium to travel unlike conduction and convection.)

Ans 5:

Class : Class 7
A is the correct answer

Ans 6:

Class : Class 8
Option c is the correct answer, because if at all any cold material is stored in the flask, then the liquid becomes hot due to the heat of the sun. Hence it is used to reflect the radiation from the sun

Ans 7:

Class : Class 7

Ans 8:

Class : Class 8
i am not sure if it is A or C

Ans 9:

Class : Class 7
OPTION C IS CORRECT ANSWER.

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