Nexus 7 users now have an alternative operating system for their device. It is unfortunately still quite rare to have an option to run an alternative operating systems on your mobile or tablet device—even as such a thing is taken for granted by desktop and laptops users. KDE developers have managed to get Plasma Active 3 running on the Nexus 7 tablet and have released OS images and instructions for those wanting to experiment with their device. The OS is based on the Mer Linux distribution. 
Plasma Active is a KDE project with the aim of developing an OS for tablets that is designed from the ground up for
touch rather than bring adapted for touch from an existing desktop OS. Mer is a Linux-based project that aims to continue the work done by the MeeGo project in making a Linux distribution that can run on mobile devices, tablets and other such form factors. A number of Linux distros that aim to run on mobile devices are based on Mer, including the Sailfish OS by Jolla. The biggest problem with running a custom Linux distro on a smartphone or tablet devices is the lack of availability of device drivers for some of the components used in the device, since the drivers are often closed source. So don’t expect everything to run smoothly when running a custom OS. If you are still up for it, and own a Nexus 7 in the first place, you can find more information and instructions here.
Thanks for information but i think alternative OS reduce efficiency and increase power consumption and also reduce processors speed
What you say bro?