What are the 2 types of crystallization ?

Select the word from the list that best fits the definition classification of most stars on the h-r diagram

Quantum mechanics applies to subatomic, atomic, nanometer-size, and micrometer-size systems. nanometer, micrometer, and kilometer-size systems. atomic, nanometer-size, and micrometer-size systems. subatomic, atomic, and nanometer-size systems.

How is sound energy produced a. vibrating objects b. objects being heated c. temperature differences d. stationary objects