[Grammar] Which hour was he born at? or Which o'clock?

[Rooby]

Hi,

I have a question to ask. Is it correct?

Which hour (of day) was he born at?
Or Which o'clock was he born at?

Thank you for help.

 

[Jill Dorchester]

Usually we'd ask "What time was he born?"

 

[Rooby]

Thank you, Jill