Our students got selected in top MNC
My question is why is 'got' used so often in sentences of this type? Can I use some another word like 'was' in place of 'got'? Would it be correct?
It's a common use. You could also say "our students were selected" or "our students have been selected" and either one would be both correct and easily understood.
This structure of get-passive is rare in all registers, but occasionally occurs in conversations. The difference between be-passive and get-passive is that the former expresses a state whereas the latter is more dynamic, describing the proccessing of getting into that state.
Our students were selected(=our students were in a state of being selected)
Our students got selected(=our students were in the proccess of becoming selected)
Get-passive usually occurs in conversations, in a written register, we usually use become.
Longman Student Grammar of Spoken and Written English, 6.7.2