A book is falling from the top shelf of a bookcase. Which statement correctly describes the change in the energy of the book? The potential energy and kinetic energy remain the same.
The potential energy decreases as kinetic energy increases.
The kinetic energy decreases as potential energy increases.
The kinetic energy remains at zero, but potential energy increases.

The potential energy decreases and kinetic energy stays the same.

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.