Answer : The number of moles of helium are, 0.329 mol.
Explanation :
To calculate the moles of helium gas we are using ideal gas equation.
[tex]PV=nRT[/tex]
where,
P = Pressure of [tex]He[/tex] gas = 92.3 kPa = 0.911 atm
V = Volume of [tex]He[/tex] gas = 8.5 L
n = number of moles [tex]He[/tex] = ?
R = Gas constant = [tex]0.0821L.atm/mol.K[/tex]
T = Temperature of [tex]He[/tex] gas = 287 K
Now put all the given values in above equation, we get:
[tex]0.911atm\times 8.5L=n\times (0.0821L.atm/mol.K)\times 287K[/tex]
[tex]n=0.329mol[/tex]
Thereofore, the number of moles of helium are, 0.329 mol.