6. Calculate the △Ssys (in R) for 1.0 mole of monatomic (單原子) ideal gas changingfrom state A (1.0 atm, 300 K) to state B (2.0 atm, 600 K).(A) 1.7(B) 1.0(C) 2.5(D) 3.2(E) 2.1