18. A radioactive element has a half-life of 18,000 years. There was 400 grams of the element originally. There is now 12.5 grams of the radioactive element left. What is the age of the
sample?

Nuclear fusion is the source of energy for stars. besides hydrogen, which other element is most likely also common in stars?

Select the correct answer. which phrase correctly describes temperature? o a. average rotational kinetic energy of the particles in an object o b. average energy of the particles in an object c. average translational kinetic energy of the particles in an object od. all energy possessed by the particles in an object

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space