ANSWER:

You must at least move your tongue and lips while making dua, dhikr, reciting Qur’an or while praying. 

As i know when a child is born 2 angels are givn charge to write the deeds till he dies. Now as fr angels don know what is in the mind and heart of a person. So if i make Doa in my mind – without uttering words – how will that be acknowledged ? Or i need to pronounce it ? Pl guide