A sample of 0.50mol of an ideal monatomic gas expands isothermally and reversibly at 300K from an initial volume of 2.0L to a final volume of 6.0L. Which of the following is closest to the change in entropy ΔS of the gas?
a) 0J/K
b) 9.1J/K
c) 4.6J/K
d) 2.9J/K