Reverberation in concert halls is caused by a. diffraction c. diffusion b. refraction d. reflection select the best answer from the choices provided a b c d

Ais a mountain created from eruptions of lava, ash, rocks, and hot gases.

Why is retrograde motion an apparent motion

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.