Which of the following is most likely to happen when a sound wave reflects off a hard surface? (Assume that neither the source of the sound nor the hard
surface is moving.)
A. A change in speed
B. An echo
C. A change in pitch
D. A beat frequency

Aaspirin has a density of 1.40 g/cm^3 what is the volume in cubic centimeters of a tablet weighing 320 mg?

Embryos of different species look very similar, which shows that the organisms share a ancestor.

Adeuteron, 21h, is the nucleus of a hydrogen isotope and consists of one proton and one neutron. the plasma of deuterons in a nuclear fusion reactor must be heated to about 3.02×108 k . what is the rms speed of the deuterons? express your answer using two significant figures.