Atypical adult ear has a surface area of 1.92 × 10-3 m2. the sound intensity during a normal conversation is about 2.13 × 10-6 w/m2 at the listener's ear. assume that the sound strikes the surface of the ear perpendicularly. how much power is intercepted by the ear?

The sound intensity is the ratio between the power of the wave and the surface:

where
I is the intensity
P is the power
A is the area

In our problem, the sound intensity is , and the surface area of the ear is , so if we re-arrange the previous equation and we use these data we can find the sound power:

The answers would be: 1: the liquid only contains one compound4: the liquid is a pure substance