Is it a condition for the mosque where I‘tikaf is performed to hold Jumu‘ah prayers?
No, it is not a condition for the mosque where I‘tikaf is performed to have Jumu‘ah prayers. However, if a person vows to perform continuous I‘tikaf, and Jumu‘ah occurs within that period, then they must observe I‘tikaf in a mosque where Jumu‘ah is held so that they do not break their continuity by leaving for Friday prayer.
How to pay Zakah (obligatory charity) due on articles of merchandise?
Articles of merchandise are estimated by their whole sale market price at the end of each lunar year, and (2.5%) of their value is paid as Zakah whether it (value) went up, or down compared to actual purchasing price, and whether the increase (profit) was in the article itself such as an increase in the animal`s weight, or in the prices themselves. And Allah Knows Best.
What is the ruling on the use of an inhaler by a *muḥrim* (a person in the state of *iḥrām*)? [An inhaler is a medicinal device used for inhalation, containing various herbal ingredients.]؟
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
It is permissible for the muḥrim (a person in the state of iḥrām) to use incense (bakhūr), sprays, and inhalers that contain aromatic substances for the purpose of treatment, because the intention is medical treatment, not the use of perfume (taṭayyub). No expiation (fidyah) is required of him for doing so.
It is stated in Ḥāshiyat al-Bujayrimī ʿalā al-Khaṭīb (Vol.2/p.455): “That which is intended for eating or for medical treatment, even if it has a pleasant scent, such as apples, spikenard (sunbul), and the various fragrant spices such as mastic (muṣṭakā), is not forbidden, and no fidyah is due for it, because what is intended for eating or treatment carries no fidyah.”. And Allah Almighty knows best.
Can Zakah or Zakat al-Fitr be given to a poor brother?
Yes, it is allowed to give Zakah or Zakat al-Fitr to a poor brother, as he is considered among the eligible recipients.