Plse help me nexus 5 32gb topic

pls i need file mmcblk0 of phone nexus 5
If phone root done
Install terminal in chplay and write
su (check allow in phone)
dd if=/dev/block/mmcblk0 of=/sdcard/nexus5.img bs=512 of=2097152
And copy file nexus5.img up googledriver help me:D
Thank you very much