The half-life for an 80-gram sample of an unknown radioactive element is 5 days. How much of the unknown radioactive element remains after 10 days have passed?

A. 20 g

B. 40 g

C. 70 g

D. 80 g

Pls help, I'll mark brainiest, I really need a good grade, so pls answer correctly.

Asmall, positively charged ball is moved close to a large, positively charged ball. which describes how the small ball likely responds when it is released? it will move toward the large ball because like charges repel. it will move toward the large ball because like charges attract. it will move away from the large ball because like charges repel. it will move away from the large ball because like charges attract.

Which statement is best supported by the information in the chart? wave y is moving the fastest. wave x is moving the fastest. all of the waves are moving at the same speed. all of the waves have the same value of wavelengths per second.

How do you tell if someone actually cares about you? and just say they do?