Please help, I'm lost

When a comet collides with earth, it adds material to our planet and causes great damage. therefore, a collision like this is a a. destructive force b. constructive force c. geologic process and event d. constructive and destructive force

One or more substances changing into one or more substances is an example of a

Two liquids are poured into a beaker. after a few seconds, the beaker becomes warm. which of the following best describes this reaction? a. an exothermic reaction b. a decomposition reaction c. an endothermic reaction d. a single-displacement reaction