Synchronous Mode for Secondary replica on a different geographic location

I've a doubt on AlwaysOn configuration and need clarification.

Is Synchronous mode allowed for a secondary replica placed on different geographical location. Example Primary replica is in India and secondary is in USA.

Does is depends weather it's a multi-subnet cluster or not.

Also, is there any other restriction for AlwaysOn in a multi-subnet cluster configuration.

Thanks,
Nitin