The moles of the gas in the sample is 0.391 moles
calculation
by use of ideal gas equation, that is Pv=nRT
where n is number of moles
P(pressure)= 660 mmhg
R(gas constant) = 62.364 l.mmhg/mol.K
T(temperature)= 25 +273 = 298 k
by making n the subject of the formula
n= Pv/ RT
n is therefore= (660mm hg x11 L)/( 62.364 L.mmhg/mol.k x298 K) = 0.391 moles
