Is it permissible to offer mandatory prayer while sitting?
All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions. Standing up is a pillar in the mandatory prayer and the prayer is not valid without it unless one cannot do it. As for Nafila (supererogatory prayer), one can perform it in the state of sitting even if he/she can stand, but his/her reward is half the reward of the person who prays while standing if he/sh has no legal excuse for such an act. And Allah Knows Best.
What is the ruling on someone who possesses cash reaching the niṣāb (minimum threshold liable for zakah), and then uses part of it to purchase gold before the ḥawl (lunar year) is complete — must he pay zakāh on all of it [combined], or only on the remaining cash, excluding the gold?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
Gold acquired for hoarding and saving is subject to zakāh once it reaches the niṣāb (minimum threshold liable for Zakah) — when combined with any cash held — and once a full ḥawl (lunar year) has elapsed over it. The starting point for calculating this ḥawl is the ḥawl of the paper currency [used to purchase it], which had already reached the niṣāb and was then used to purchase the gold.
It is stated in Mughnī al-Muḥtāj (Vol.2/p.78): "As for someone who sells silver in exchange for gold, or vice versa, zakāh remains obligatory upon it, since he builds [the calculation of] its ḥawl upon [the ḥawl established at the time of] the original transaction [i.e., when the wealth was first acquired]."
This has already been explained in detail in Fatwa No.
2670 — please refer to it.
And Allah, the Exalted, knows best.
Is it a condition for I‘tikaf to be performed in the mosque?
Yes, for I‘tikaf to be valid, it must be performed in a mosque. I‘tikaf is not valid if performed at home or elsewhere.
What is the ruling on making up the regular pre-Dhuhr *sunnah* (*al-sunnah al-rātibah al-qabliyyah*) for one who missed it in the Dhuhr prayer?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Every timed supererogatory prayer (nāfilah) is recommended (mandūb) to be made up if its time passes. As for a nāfilah that precedes the obligatory prayer, performing it before the farḍ is a matter of proper etiquette (adab); if it is prayed after the farḍ, it is still considered adāʾ (performed within its time). If the time of the farḍ has ended, it is recommended to make up (qaḍāʾ) the nāfilah for one who did not pray it.
Whoever misses the sunnah before Dhuhr, whether with an excuse or without one, it is recommended for him to pray it after the obligatory Dhuhr prayer, within the time of Dhuhr, even at its end, and it counts as adāʾ, not qaḍāʾ. It is also recommended for one who missed the pre-Dhuhr sunnah to pray it before the post-Dhuhr sunnah, in observance of the proper order. It is stated in ʿUmdat al-Sālik wa ʿUddat al-Nāsik (Vol.1/p.60): "What precedes the obligatory prayer has the same time as the obligatory prayer, and performing it before the farḍ is a matter of etiquette; after it, it is adāʾ. What follows the farḍ has its time begin with the performance of the farḍ and end with the end of its time."
If the time of Dhuhr has ended, it is recommended for him to pray both the pre- and post-Dhuhr sunnahs, and they count as qaḍāʾ for both. It is stated in ʿUmdat al-Sālik (1/61): "Every timed nafl, such as the ʿĪd prayer, Duha, Witr, and the regular rawātib of the obligatory prayers, if it is missed, it is recommended to make it up forever." And Allah Almighty knows best.