What is the semi-circular structure attached to the Holy Kabah?
The semi-circular structure attached to the Holy Kabah is Hijr Al-Kabah (is a low wall originally part of the Kabah) and passing behind it is an obligation while making Tawaf because it is a part of the Holy Kabah. And Allah Knows Best.
I am an employee at Social Security, and I have heard that working with them is forbidden (haram) because they impose an interest rate of 2% on companies and individuals who are late in making payments. Is my job with them haram or questionable?
Please clarify the type of work. If it does not involve the usury (Riba) mentioned, we hope that there is no issue with it, as most of their funds are acquired in a lawful (Complies with the teachings of Sharia) manner. And Allah, The Almighty, Knows Best.
Is it permissible to give lessons to mixed students of the seventh grade?
It is impermissible to give private lessons to mixed students since such an act leads to serious consequences for the students in this grade are teenagers.
Should the Zakah (obligatory charity) giver tell the poor recipient that this is the Zakah of his money?
No, he shouldn`t. But, the Zakah giver should make an intention in his heart that it is the Zakah of his money when paying it to the poor. And Allah Knows Best.