Ideal gas equation.
PV = nRT
Pressure * volume = moles gas * constant * temperature in Kelvin
PV = nRT
Algebraically manipulated to get temperature.
T = PV/nR
T = (1.95 atm)(12.30 L)/(0.654 moles He)(0.08206 L*atm/mol*K)
T = 447 Kelvin
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At what temperature will 0.654 moles of neon gas occupy 12.30 liters at 1.95 atmosphere?