If a liquid is heated in space under no gravity, the transfer of heat will take place by process of

CONCEPT: 

• The movement of energy from one place to another is called energy transfer. Heat transfer mainly takes place due to temperature differences.
• There are three modes of Heat transfer.
  1.Conduction: The mode of heat transfer in solids where heat transfer takes place without the movement of medium particles is called conduction.
  For example:  By heating one end of a metal rod we can feel hotness at another end.
  2.Convection: The mode of heat transfer in fluids where heat transfer takes place due to the movement of particles of the medium is called convection.
  For example: Heating of water in a pot
  3. Radiation: The mode of heat transfer where heat is transferred from one place to another without affecting the medium particles is called radiation.
  For example: When we place our hand nearby the burning gas stove then we can feel the hotness. This is due to radiation.

EXPLANATION:

• From above it is clear that the process of the transfer of heat from one place to another place without heating the intervening medium is called radiation.
• It is possible to even in vacuum e.g. the heat from the sun reaches the earth through radiation. Therefore option 3 is correct.