Salam Alaikum Ustadh, Is it permissible to keep the Quran (Mushaf) on the floor while I am sitting or lying down and reading from it ? Does it apply to Quran in Mobiles too ? JazakAllah Khair

Put it somewhere elevated like a shelf or a chair better, and if there was a need for it and you put it on pure ground to make sujud for example of recitation or something else, then there is no harm.