What is the ruling on unhijabed girls going to pray in mosques while respecting their sanctity?

It is not permissible for a woman to go out to the mosque adorned (mutabarrijah), and her prayer is invalid if her head is uncovered. As for uncovering the face in prayer, the preponderant opinion is that it is not obligatory if she is not in the presence of men, and her prayer is valid, with the preference for her praying in her home. As for outside of prayer, the preponderant opinion is the obligation of covering the face, by consensus if there is fear of temptation (fitnah). Muslim women must fear Allah and adhere to modesty and chastity when going out, and not display their adornment.