NextMockपरीक्षा शोधा, उदा. SSC CGL, UPPSC, Lekhpal
State PCS PYQPrelims 2019

UPPCS · प्रश्न 50

A liquid remains hot or cold for a long time in a thermos flask because there is no loss or gain of heat by

  1. Conduction
  2. Convection and radiation
  3. Both (a) and (b)
  4. None of the above
उत्तर दाखवा आणि स्पष्टीकरण

उत्तर: (C) Both (a) and (b)

स्पष्टीकरण

A vacuum flask's double wall with a vacuum stops conduction and convection, and the silvered surfaces cut radiation. So heat is not gained or lost by either (a) or (b).