ANSWER:

Separate sujud for dua after Salah is prohibited and innovation.You can make any dua during sajdah in obligatory or nafl prayers.

If you do not know the Dua in Arabic, it is permissible to make dua in any other language. 

https://youtu.be/hYToZVeAl20

What is the ruling of Dua in prostration. Can i pray anything in any language in prostration regardless of whether its obligator or nafle prayers? Or can i just make sujood for dua after the salath finished?

Prayer | November 21, 2019 11:44 pm
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I read that it is recommended that the hearer of the iqamah should repeat it after the muqim (the one who announces the iqamah), and when he says “Qad qamati-s-Salah” the hearer should respond by saying: Aqamaha-llahu wa adamaha (May Allah keep it established forever). If incorrect, please inform what is 2 be said when the Muqim announces the Iqamah and esp when he says ‘Qad Qamataissalah’.
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Sheikh, where I am staying there are small masjid in each of the block where most of the time, people can pray alone. Also, there is a big masjid close to where I am staying where people pray in jamah, but in this masjid, they always leave space in between one another,and if I try to move closer they move there feet away. This is the norm in this country. Is it okay to pray alone?