You can make any GNU/Linux bootable USB very easily by using GNOME Disk Utility program included in Ubuntu by default. This program named “Disks” on your Ubuntu menu. This means you don’t need to install any additional program to do it, and even you can do it directly from a Ubuntu live session. It’s just like having Unetbootin or Rufus program built-in. What you will do with this program is just loading a .iso file and write it into USB drive.
Select USB Drive
Press “Restore” Button
Select ISO File
Enter Root Password
While it’s finished, you will find GNOME Disk Utility shows the content of your USB drive. Typically, you will see the name of your GNU/Linux operating system as the name of the first partition on the USB volume map shown.