Home
Class 12
PHYSICS
Statement I : A thermos flask is made of...

Statement I : A thermos flask is made of double-walled glass bottles.
Statement II: Metals are goog. conductors while gas and air are poor conductors of heat

A

Both the statements indi_vic,iμallytrue and Statement II is the correct explanatien ofStatement I.

B

Both the statements are jndividually true but Statement II is not correct explanation of Statement I

C

Statement I is true but Statement II is false

D

Statement I is false but Statement II is true.

Text Solution

Verified by Experts

The correct Answer is:
A
Glass fairly strong and rigid, and 2 thin layer of glass can withstand the pressure differences created by the vacuum. It is also easy to manufacture the required shape, and keep it airtight. Also it is almost perfectly transparent, meaning that once the surface is mirrored, it will reflect almost all of the radiated heat. Plastics would be too flexible to contain the vacuum effectively, and metals would be too conductive, and the mirrored surface would not be so good.
Promotional Banner

Similar Questions

Explore conceptually related problems

Statement- 1 : Snow is better insulator than ice. Statement - 2 : Snow contain air packet and air is a bad conductor of heat.

Statement - 1 : When hot water is poured in a beaker of thick glass, the beaker cracks. Statement - 2 : Glass is a bad conductor of heat and outer surface of the beaker does not expand.

Thermos bottle or Dewer flask consists of a double walled glass vessel with inner and outer walls coated with silver. Give reason.

Statement I : All liquids are conductors of electricity. Statement II : Under the condition of low pressure and high voltage, liquids can be made conducting.

Which of the following statements are correct for carbon compound? (i) Most carbon compounds are good conductors of electricity (ii) Most carbon compounds are poor conductors of electricity (iii) Force of attraction between molecules of carbon compounds is not very strong (iv) Force of attraction between molecules of carbon compounds is very strong

Statement I : Sodium metal reacts violently with water to produce heat and fire. Statement II : Potassium metal reacts violently with water to form potassium hydroxide and hydrogen gas. Select the correct answer from the options given below :