I am trying to install Ubuntu as as desktop usage on an Acer C7 Chromebook. I have downloaded it but it is asking for an app to open it. Is there such an app?
Is it possible to do this?
There's a Chrome app called Crouton that lets you do this without removing ChromeOS, but your device has to be in Developer Mode first, which means that your device is in an unsafe mode so I wouldn't recommend it unless you know exactly what you are doing and are aware that this could potentially break your device.
That said, good instructions for enabling developer mode and running Ubuntu can be found at this link. on HowToGeek.
Here you have a video to how to install Ubuntu 12.04 in your Acer C7 Chromebook:
And if you need more help, you have some tutorials (2 first results from Google):