we use the formula
pV=nRT
we convert Kilo Pascals to mmHg
253.25 KPa=253250 pascals
1mmHg is equal to 133.322 pascals
xmmHg are equal to 253250pascals
x=253250/133.322=1900mmHg
now we convert mmHg to atmospheres
1 atmosphere is equal to 760mmHg
x atmospheres are equatl to 1900mmHg
x=1900/760=2.5 atmospheres
in the formula:
pV=nRT
p-pressure
V-volume
n-number of moles
R-ideal constant of gases
T-temperature
the only missing variable is temperature since we know that R=0.082
250ml=0.25L
0.25*2.5=0.1*0.082T
T=0.625/0.0082=76.219K