How is the half-life of a radioactive isotope determined? A. By measuring the time it takes for half the parent nuclei in a
sample to become daughter nuclei
B. By measuring the time it takes for half the daughter nuclei in a
sample to become parent nuclei
C. By measuring the time it takes for all the parent nuclei in a sample
to become daughter nuclei
D. By measuring the time it takes for all the daughter nuclei in a
sample to become parent nuclei

Which of the following is not a part of the respiratory system? a. pharynx b. trachea c. pancreas d. larynx

Choose the most likely outcome of this scenario: jen decided to go bike riding without a helmet. while no one is around during her ride, she is thrown from her bike when her wheel goes into a pothole. she is not injured, but she is terrified to get back on her bike. what happens next? a. her physical health is affected even though she wasn't hurt. b. her mental and emotional health are affected because she is afraid to get back on her bike. c. her social health is affected because she is worried her friends saw the fall. d. her overall health is not affected at all by her fall.

The seven sisters, seven stars located more than 400 light-years away in the taurus constellation can be seen here with venus and another constellation, orion. the seven stars stay grouped together but seem to move, like the planet venus. why do stars seem to move like planets in the night sky?