Question

how to use pendrive as bootable device

Answer 1

Pendrive can be used as a bootable device by copying bootable files to it with specific program.Simple copying of the bootable file is of no use.

For example one program to make bootable pendrive with bootable iso file.Other programs to make bootable pendrive are WinUSB Maker , Universal USB Installer(linux)

Answer 2

pen drive can be used as a bootable device by coping bootable file to it with specific program it is not use of simple coping file