Is the niṣāb calculated based on the price of 21-karat gold, or 24-karat gold?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
Zakāh is obligatory on cash and on gold designated for saving or for trade, provided the total reaches the niṣāb (minimum threshold liable for zakah), and a full ḥawl (lunar year) has elapsed over it. The niṣāb is (85) grams of 24-karat gold; for 21-karat gold, the niṣāb equals (97) grams; and for 18-karat gold, it equals (113) grams.
The relied-upon position is to calculate the zakāh based on the buying price [i.e., the price the gold merchant would pay the owner to purchase the gold from him] on the day the zakāh obligation is due.
The one paying zakāh may assess/calculate the niṣāb using any of the aforementioned gold karats [i.e., he may choose whichever karat standard he wishes for the purpose of the calculation]. And Allah, the Exalted, knows best.
Which is better in night prayer: long standing (Qiyam) or long prostration (Sujood)?
Long standing (Qiyam) is better in prayer. However, a Muslim should also observe tranquility and composure in their prayer.
There are olive trees within the precincts of the mosque, and my father covers the costs of electricity, water, and other needs of the mosque. Is it permissible for him to take the olive harvest?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
If trees and fruit-bearing crops are planted in a mosque for the mosque itself, they may only be spent on the mosque’s interests. If they were planted for the public way (musabbalah), that is, for the general public, then any Muslim who enters the mosque may eat from them. If the planter’s intention is unknown, they are treated like those dedicated for public use, wherever custom has so run.
It is stated in Tuḥfat al-Muḥtāj (Vol.6/p.295): “The fruit of a tree planted for the mosque within it is not freely permitted without compensation. Rather, the imam spends its equivalent value on the mosque’s interests. The tree left its planter’s ownership here without any verbal declaration because of the evident indication. The case of planting it for the mosque excludes planting it as musabbalah, in which case eating from it without compensation is permissible, and likewise if his intention is unknown, where custom has so run. The tree may be uprooted from the mosque if the imam sees fit. Indeed, if he makes the plot a mosque while a tree stands in it, the imam may uproot it, even if the endower included it within the endowment (waqf).”
The father is a donor (mutabarriʿ), so he is not entitled to take anything in return for his donation to the mosque.
The Ministry of Awqāf is the body that supervises the affairs of endowments, so it must be consulted and the Sharīʿah and administrative instructions regulating such matters must be considered. And Allah Almighty knows best.
What is the ruling on using a miswak (tooth-stick) during the day in Ramadan?
It is permissible to use a miswak before noon while fasting. However, according to the Shafi'i school, it is disliked (makruh) after noon in order to preserve the natural effect of fasting in the mouth, as the Prophetﷺ said in authentic hadith:
"The breath of a fasting person is more pleasant to Allah than the fragrance of musk."