Why do most surfaces reflect light diffusely? 1. most surfaces are clear. 2. most surfaces are 100% smooth. 3. most surfaces are not totally smooth. 4. all surfaces are smooth.

First answer marked as brainiest which is the correct equation describing the first law of thermodynamics? a) when the internal energy of a system changes, it equals the amount of heat added plus the work done. b) when work is done by the piston, it is equal to the heat added plus the change in internal energy of the system. c) when heat is added to the system, it is equal to the amount of work done by the piston plus the change in internal energy of the system.