What causes molecules in the air near lightning to make the sound known as thunder?

Me with these questions if you’re it sure don’t answer

Explain how the number of similarities between the embryos from early stage to late stage is used as evidence of a common ancestry

Which of these would most likely be a stimulus that would cause the body to initiate feedback mechanisms a.) normal body temperature in an arctic environment b.) normal boy temperature in a tropical environment c.)light physical activity d.)low blood sugar