1. Two sound waves are traveling through a container of unknown gas. Wave a has a wavelength of 1.2m. Wave b has a wavelength 3.6m. The frequency wave b must be ______ the frequency of wave A.

A. one-ninth
B. one-third
C. the same as
D. three times larger than

2. What is sound energy?

A. It is moving electrons
B. It is plain kinetic energy
C. It is energy that travels in waves through vibrating matter
D. It is energy that travels in waves like light from the stars

3. Hertz(Hz) is the measure of sound wave frequency. It measures how many waves pass between two points in one second. If there are 30 waves that pass in second, what is the sound's frequency in Hz?

A. 15 Hz
B. 20 Hz
C. 25 Hz
D. 30 Hz​