(a)[1]
Sound moves at the same speed as light. Sound moves more quickly than the speed of light. Sound moves more slowly than the speed of light.
(b)[1]
Healthy human ears can detect sounds in the range 2.0 Hz to 2000 Hz. Healthy human ears can detect sounds in the range 20 Hz to 20000 Hz. Healthy human ears can detect sounds in the range 200 Hz to 200000 Hz.
(c)[1]
Making the amplitude of a sound wave larger increases its speed. Making the amplitude of a sound wave larger increases its frequency. Making the amplitude of a sound wave larger increases its loudness.
(d)[1]
An echo is produced when sound undergoes diffraction. An echo is produced when sound undergoes refraction. An echo is produced when sound undergoes reflection.