What might you expect for the value of S∘ (entropy) for butane, C4H10?
Entropies provided (Hint: entropy increases with increasing molecular complexity):
- CH4=186.3(J/mol*K)
-C2H6=229.6(J/mol*K)
-C2H8=270.3(J/mol*K)

340 J·K⁻¹mol⁻¹  

Explanation:

I looks like the standard entropy increases approximately linearly with the number of C atoms.

I plotted S° vs the number of C atoms and got the graph shown below.

It appears that S° for four carbon atoms should be about 340 J·K⁻¹mol⁻¹.·