Is wearing a white thobe without long trousers considered to expose the 'awrah (private parts)? What is the ruling on the prayer of one who is in this state, praying behind the Imam, while being aware of the necessity of covering the 'awrah? And how does one make up for the prayers if their number is unknown?

Among the conditions for the validity of prayer is "covering the awrah" (private parts), so prayer is not valid without it, due to the Almighty’s saying: (O Children of Adam, take your adornment at every masjid). For a garment to be a cover, it must conceal the color of the skin. If the color of the skin shows through it, then it is not considered a cover, and prayer performed with it is not valid. The criterion for a cover is that an observer cannot distinguish the color of the skin (its whiteness, redness, or blackness). If a garment is transparent and reveals the color of the skin, it is not a cover, and prayer performed in it is not sufficient. Thus, whoever wears short trousers that do not cover what is between the navel and the knee, and wears a transparent garment over them, has not covered their awrah, and their prayer is not valid.