Pick the answer that correctly completes the sentence: As a sound wave approaches an observer, the frequency will , the wavelength will and the speed of sound will O decrease; increase; stay the same O increase; increase; increase increase; decrease; stay the same O decrease; decrease; increase QUESTION 5 On a piano, there are octaves between 55 Hz and 220 Hz. QUESTION 6 What is the frequency of a wave with a speed of 600 m/s and a wavelength of 8 meters? O 75 Hz O 0.013 m/s O 4800 Hz O 0.075 Hz QUESTION 7 Sound waves propogate through materials as pressure or longitudinal waves. O True O False