Your Answer to Q35. Sorry, your answer is not correct. Think what happens to the wave on a rubber rope when it hits a wall. Your Answer to Q35. Congratulations, your answer is correct .
Sound waves behave in a similar manner.
When the sound wave in a canyon hits a hard wall most of the wave energy will be reflected back as an echo because the wall has so much inertia and little wave energy actually enters the rock. It helps to have a narrow canyon, because the wave energy is then channeled down the canyon rather than spreading out over a broad area and becoming less loud. Thus one can make a quiet room by having a lot of carpeting, drapes, and soft furniture. Your Answer to Q40. Sorry, your answer is not correct.