NextMockપરીક્ષાઓ શોધો, દા.ત. SSC CGL, UPPSC, Lekhpal
State PCS PYQPrelims 2019

UPPCS · પ્રશ્ન 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
જવાબ બતાવો અને સમજૂતી

જવાબ: (C) Both (a) and (b)

સમજૂતી

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).