Define the following units used for measuring distances in space. a. Arcsecond
b. Astronomical unit
c. Parsec
d. Light year

This is what i found on google “according to the collision theory, the following criteria must be met in order for a chemical reaction to occur: molecules must collide with sufficient energy, known as the activation energy, so that chemical bonds can break. molecules must collide with the proper orientation.” i hope this information you.