Answer: Diagram 1 (with the blue balls).
Explanation:
1) After the solids melt they are liquids.
Liquid state is characterized by the particles being close but yet free to move, they can slip over each other, which is what permit the liquids flow and take the shape of the containter.
2) Solid is the state of the matter in which the particles are stuck together, they cannot move with respect to the others, but they are in fixed positions. In this state the particles vibrate and the matter has a definite shape and volume.
This state is represented by the diagram 3 (the red balls).
3) In gas state the particles are quite separated, free to move in and occupy all the space. In this state the particles are moving at great speed. The volume of the gas is the volumen of the container.
This state is represented by the diagram 2(the yellow balls).
4) Plasma is the state of the matter similar to gas state but the particles are ions. Those are particles that have charge, either positive or negative.
This is represented by the diagram 4 (the balls with positive and negative symbols).