two scientists are experimenting with pure samples of isotope x, a highly radioactive substance. the first scientist has a sample with a mass of 20 grams. he measures a half-life of 232 seconds. the second scientist has a sample of the same substance with a mass of 80 grams. what is the half-life that she is most likely to measure?
a. 58 seconds
b. 232 seconds
c. 464 seconds
d. 928 seconds

During the apollo moon missions, astronauts were concerned about the effects of newton's third law of motion when: o a. they ejected waste water, because they were concerned that it would push them off course. o b. they reentered earth's atmosphere, because they were carrying heavy moon rocks. o c. they took off from earth, because a large force was required to generate large acceleration. o d. they detected incoming space debris, because the inertia of the debris could damage their ship.