Questions

Activation energy is a minimum amount of energy that required for the chemical reaction to happen or to take place.

Sound waves cannot travel through a Vacuum.

A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.

Testing is a process used for revealing defects in s/w and for establishing that the s/w has attained a specific degree of quality.

The s/w testing group’s main objective is to ensure that the s/w is doing what it is supposed to do as well as the s/w is not doing what it is not supposed to do. With this objective, it is clear that it is necessary to have a separate group for testing the s/w other than the group which developed it.

Also, bugs in the s/w can cause severe monetary as well as other loss to the organization. So it is important to allocate some budget for the testing group.

Footsteps. 

Yes, as you walk forward, you will leave the footstep behind you.