Explanation:
A catalyst means "something that causes activity,an event, or change." And usually,these events and changes are big.
I hope it's helpful!
Answer:
Velocity
Explanation:
The change of velocity rate it's the definition of acceleration.
While increasing or decreasing velocity, it means that an acceleration it's happening.
Using some math:

This can be read as "the acceleration it's equal to te variation of velocity with respect to time"
Answer:
Carbon dioxide gas
Explanation:
When an animal breathes, it takes in oxygen gas and releases carbon dioxide gas into the atmosphere.