Why are light and sound not considered as matter

The "particles" of light are called photons and have no mass,

Matter is made up of particles that do have mass.

Explanation:

Well, light is faster then sound Obviously, so that is why they are Not considered as Matter.  

- Swish

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.