Air at 273K and 1.01*10^5 Nm^(-2) pressure contains 2.70*10^(25) molecules per cubic meter. How many molecules per cubic meter will there be at a place where the temperature is 223K and the pressure is 1.33*10^(-4) Nm^(-2)?

I know this has got to do with ratios.
I found n=(pV)/RT for both temperature and pressures
They were 44.50 and 7.17*10^(-4) for 273K and 223K respectively. this would be the number of moles in the air right? when V is 1 cubic meter.
now 7.17*10^(-4)/44.50=1.612*10^(-5)
then i took this number and multiplied it by 2.70*10^(25) and got 4.35*10^(20).
The answer is supposed to be 4.35*10^(10).
so i've got it off by a magnitude of 10^(10).
Where have i gone wrong?
Thanks

__________________
To each his own.

Hi Arze

I think your calculation to find 7.17 * 10^(-4) is wrong, I got 7.17*10^(-8).

But the final answer will be 4.35 x 10^(16), which is still not the same as the manual...I wonder what I've missed....

yes you're right its 7.17*10^(-8), yeah its something i missed.
Thanks anyways

__________________
To each his own.