CHEMISTRY COMMUNITY

Why on question 1C of the 2011 final would NO have a greater residual entropy than BF3 at OK?

Because NO has 2 orientations: ON or NO, and oscillation between these two possible configurations contribute to higher residual entropy. BF3, on the other hand, has only 1 possible configuration. No matter how you rotate the trigonal planar, you'll get exactly the same configuration.