1. The library is open from 9 to 5.

2. The library is open 9 to 5.
3. The library is opened from 9 to 5.
4. The library is opened 9 to 5.
[Are they all grammatical?]

2 answers

I think the first one would work best, and the second would be okay as well. However, the third and fourth answers don't sound quite right.
The verb "is" is present tense. The word "opened" is past tense. They don't agree. It either WAS opened from 9 to 5 at some time in the past, or it IS open from 9 to 5 on an on-going basis. Numbers one and two are both acceptable (Kathryn is right, #1 is better). Three and four are not.