For a chemical reactions in a closed system mass cannot be

The primary purpose of a certificate of confidentiality is to: allow law enforcement to investigate abuse cases.protect researchers from disclosing conflicts of interest.prevent subjects from knowing the purpose of a study.protect identifiable research information from compelled disclosure.

What obstacles did jen bricker face early in life?

Spanish for "estate," this was a type of plantation or other economic activity in spain's "new world" colonies.