Is a pair of trousers considered impure if a menstruating woman tries them on, and must they be washed before being worn? And must the Maghrib and Isha prayers be combined on a plane when traveling, and how are the two prayers combined?

The trousers do not become impure merely by being worn by a menstruating woman, unless they come into contact with menstrual blood.

The Dhuhr prayer is performed when its time begins, and it is permissible to delay it to combine it with Asr, provided one leaves the city before the time expires. However, if there is a concern that the time will expire before departing the city, then it becomes obligatory to perform it. If the airport is outside the city, it is permissible to combine Dhuhr and Asr.

As for Maghrib and Isha, it is permissible to combine them either by praying them earlier (taqdim) or delaying them (ta'khir) if their time begins after departing the city. It is preferable to perform them after disembarking from the airplane before the time for Isha expires, in order to avoid the disagreement of those who invalidate prayer performed on an airplane. If the airplane does not land before the time expires, then prayer within it becomes obligatory.