I am an author, and I have books stored with me. Is it permissible to pay my zakat in the form of books containing beneficial knowledge for poor students, such as chemistry and mathematics, or religious books that spread Islamic sciences?
Zakat on wealth must be paid in cash from the wealth itself. Therefore, you should pay your zakat in monetary form so that the poor can purchase what they need. And Allah Knows Best.
What should a person, who doubts the validity of his Wudu, or over performs it, do?
One who doubts the validity of his/her Wudu while performing it should redo it until he/she is certain of having attained purity. But, if doubt was after having performed Wudu, then he/she should not pay attention to that as doubt after the end of an act of worship does not count. This is of course in case doubt was within the reasonable limits since once it goes beyond that, it becomes a whispering of the Shaytaan (devil) which he/she should ignore as the Wudu is valid.
Is it permissible to offer one Rak`ah in Witr prayer?
The minimum of Witr (An odd number prayer performed between Isha`a and Fajr) prayer is one Rak`ah, and the maximum is eleven, but the minimum of its complete form is three, and it is permissible to offer one only.
My maternal aunt`s son is living abroad; however, both our families have recited Al-Fatehah declaring our engagement. We have been engaged for three months, but the marriage contract wasn`t concluded because he couldn`t come to Jordan since my mother and brothers are abroad. Is it allowed that he sees my picture without Hijab knowing that the marriage contract will be concluded at the first opportunity?
All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon Prophet Mohammad and upon all his family and companions.
Betrothal is a promise to marry, so your betrothed is a stranger to you and isn`t permitted to look at you even through a picture. Once your marriage contract is concluded, you become husband and wife and he can look at you as much as he wants. Moreover, he may deputize his father to carry out the procedures of the marriage on his behalf. And Allah The Almighty Knows Best.