Answer:
Explanation:
One of the properties of a liquid is that, it's particles move freely (not tightly packed) hence the reason for it's free flowing (no definite shape) when shaken in a container, unlike a solid whose particles are tightly packed with restricted/no movement and hence the reason for it's compactness and it's definite shape.
When a plastic solid (whose particle is tightly packed and have a restricted movement/no movement) is placed near a heat source, it's particles gains energy in the process and starts to move (though slightly free) and become less tightly packed hence the reason it is observed that plastic solids near a heat source melts.
From the above, it can be deduced that a liquid and a plastic solid near a heat source have there particles move freely (and not tightly packed) hence making the two substances flow freely with no definite shape.
