To calculate the entropy change for an isothermal compression of an ideal gas, we can use the formula:S = n * R * ln V2/V1 where S is the entropy change, n is the number of moles, R is the gas constant 8.314 J/mol*K , V1 is the initial volume, and V2 is the final volume.Given:n = 1 mole since it's one mole of helium gas R = 8.314 J/mol*K gas constant V1 = 10 L = 0.01 m initial volume, converted from liters to cubic meters V2 = 2 L = 0.002 m final volume, converted from liters to cubic meters Now, we can plug these values into the formula:S = 1 mol * 8.314 J/mol*K * ln 0.002 m / 0.01 m S = 8.314 J/K * ln 0.2 S -11.53 J/KThe entropy change when one mole of helium gas is compressed isothermally at 298 K from a volume of 10 L to 2 L is approximately -11.53 J/K.