These questions are on gas laws.

If I had 25.0 grams of methane, how many moles of CH4 would I have?

If I had the above moles of methane in a sealed 1.55 Liter container at 25C, what would be the pressure in the container in the atmosphere?

.If I cooled down the same number of moles in the same container to 12C what would be the pressure in the atmosphere?

Did the pressure in the container increase or decrease? Explain why it happened.

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.