Which postulate of the kinetic-molecular theory best describes the event in the diagram?
Most of the volume of a gas is empty space.
All collisions between particles are perfectly elastic.
There is no force of attraction or repulsion between gas particles.
The /erage kinetic energy of particles denandir onu

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

im not exactly sure but i think its b!