The inner walls of a vacuum flask have a silver coating to reduce heat loss by radiation.
<u>Explanation</u>:
The vacuum flask has an inner silver lining to prevent the transfer of heat by radiation. Radiation is a process where the emission or transformation of energy happens in the form of wave or the particles through the material medium.
Vacuum flask being working as thermal insulator helps in maintaining the substance its actual temperature for a long time. The silver lining acts as a reflector .It prevents the heat radiation to released out of the flask.
Answer: the longitude line rotates with Earth, 360 degrees in 24 hours.
Explanation: In the old days, the position of the sun was used to tell which time of the day it is. But more modern findings, has shown that the longitude line matters too.