Is it permissible to use the prayer hall as an examination room for female students and close it during prayer times, thereby depriving worshippers of performing congregational prayers in it?

If a hall is designated for prayer and endowed for that purpose, it holds the ruling of a mosque. It is not permissible to use it for examinations during prayer times if worshippers need it. However, if it is made a place for prayer without being endowed, it does not take the ruling of a mosque, and it is permissible to use it for any lawful purpose.