In an experiment, a flashlight and a buzzer are each placed in a vacuum chamber connected to a vacuum pump. They are switched on, and the air is slowly removed from the chamber. A sensor placed outside of the vacuum
chamber records the output of each device.
vacuum chamber
Device Vacuum Pump
Device Detected at
Sensor
Sensor
on
no
buzzer
off
yes
Vacuum
pump
on
yes
flashlight
off
yes
Which conclusion does the experiment support?
A. Sound waves travel farther than light waves.
B. Sound waves need a medium to travel
C. Light waves travel slower than sound waves.
D. Lightwaves need a vacuum to travel.

put the answers   and i could answer.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.