Can I run Ubuntu desktop x86 applications On Ubuntu For Android?
No, you need ARM executables (or whatever the underlying architecture of your device may be).

The only way to get around it, apart from compiling from source or finding an ARM version of the package, would be some sort of virtualization.  I don't know of any virtualization tools built for ARM myself, but at least some versions have virtualization extensions so there is the possibility of hardware-accelerated VMs.