Is a 28 good act score for sophomore?

A 28 on the ACT is a good score, especially for a sophomore. It's above the national average. However, whether it's "good enough" depends on the student's goals. If they're aiming for highly selective colleges, they might want to aim higher. But for many colleges, a 28 is a very competitive score. The most important thing is to focus on improvement and consistent studying, rather than fixating on a single number at this stage.