Which condition must exist in order for conduction to occur between two substances? the molecules of the substances must be touching. both substances must be the same temperature. at least one substance must be a liquid. most of the molecules must be slow moving?

In order for thermal conduction to exist between two substances the molecules of the substances must be touching.

Explanation:

Heat can be transfer in three ways, thermal conduction, thermal radiation and thermal convection.

In thermal conduction, the heat is transferred by the collisions between 2 particles, from the one with higher energy to the one with lowest energy.

So, in order for thermal conduction to exist between two substances the molecules of the substances must be touching.

If both substances have the same temperature, they both have the same energy so there won't be any transfer and if the particles are touching there is thermal conduction, it doesn't matter the state of the matter or the speed they are moving at.