3. If a sound is louder or a light is brighter, what does this mean about the amplitude of
the wave?
a. The amplitude is smaller
b. The amplitude is greater
c. The amplitude is always the same
d. The amplitude is louder

4. If a sound is softer or a light is dimmer, what does this mean about the amplitude of
the wave?
a. The amplitude is smaller
b. The amplitude is greater
c. The amplitude is always the same
d. The amplitude is louder

for 3. I would say it means that the amplitude is greater because if a sound is louder that means the amplitude is larger, same with the light.So that would mean the softer the sound the smaller the amplitude same with the dim of the light so for 4. It would be the amplitude is smaller. Hope this helps! :) ( if you have any questions feel free to ask)

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)