Are the following sentences acceptable?

1. What's it?

2. That's it.

Thanks a lot for your reply.
'That's it' is common, by itself. 'What's it' is common enough in a form like, 'What's it like?': 'What's it like to live near the ocean?' 'What's it like to fly a helicopter?'
This question is double-posted. Please avoid double-posting.

see contractions