Occurred to him

Hi,

Are these sentences correct? Thank you very much. Actually I'd like to know the synonyms of "occur to" and their usages.

1. It occurred to him that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.

2. It struck him that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.

3. It came to mind that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.

4. It popped into his mind that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.

5.The thought crossed his mind that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.

6. The thought entered his mind that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.

7. It sprang to his mind that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.

8. The thought that he hadn’t seen his elderly neighbour for several days was on his mind, so he finally called round to see if she was OK.

9. He couldn't get off his mind the thought that he hadn’t seen his elderly neighbour for several days, so he called round to see if she was OK.