is ios10 on my iPhone compatable with my mac os 9.1.2?

You need an OS X of 10.9.5 or later in order to run iTunes 12.5 or later, which is required to sync with a device running iOS 10.

Cheers,

GB

There is no version of the classic Mac OS or the later macOS with version 9.1.2. Perhaps you have mistaken macOS with Safari 9.1.2?

To find your macOS version,

1. Click on the Apple icon on the top left of the screen
2. Click the "About this Mac" item
3. The name and version number will appear below this (e.g. El Capitan - version 10.11.6)

Good luck and let us all know if this worked for you.