Problem 4: According to the Sackur-Tetrode equation, the entropy of a monatomic ideal gas can become negative when its temperature (and hence its energy) is sufficiently low. This is absurd, so the equation breaks down at low T. Pretend that Helium remains a gas at low T, and we keep N /V fixed. Below which T would the Sackur-Tetrode equation predict that S is negative?

Problem 4: According to the Sackur-Tetrode equation, the entropy of a monatomic ideal gas can become negative when its temperature (and hence its energy) is sufficiently low. This is absurd, so the equation breaks down at low T. Pretend that Helium remains a gas at low T, and we keep N /V fixed. Below which T would the Sackur-Tetrode equation predict that S is negative?