Does the time of Fajr (dawn) prayer start after the first Athaan (call for prayer), or the second one?
All perfect praise be to Allah,The Lord of The Worlds The time of Fajr prayer starts after the second Adhan. And Allah Knows Best.
How is the niṣāb (minimum threshold) of gold calculated when one owns gold of multiple different karats?
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.
If one owns gold of multiple different karats, the person paying zakāh should calculate the monetary value of all the gold he owns, combining these values together to determine whether the total reaches the niṣāb. He then pays zakāh on this combined monetary value, once the total reaches the niṣāb. 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. And Allah, the Exalted, knows best.
Is ablution invalidated when blood comes out of the nose, or a wound?
Blood coming out of the nose, or a wound does not invalidate ablution, but it is preferable to make ablution as a way out of the scholars disagreement in this regard.
What is the ruling on one who wiped over his leather socks (*khuff*) while resident and then traveled, or wiped while traveling and then became resident? And likewise, what is the ruling on one who incurred a minor ritual impurity (*ḥadath aṣghar*) while resident, then traveled and wiped while traveling?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Whoever wipes over his leather socks (khuffayn) while resident and then travels, or wipes while traveling and then becomes resident, before a day and a night have passed in both cases, completes the wiping period of a resident. If he wipes while resident and then travels after a day and a night have passed, he must remove the socks, because the period has ended. Likewise, if he wipes while traveling and then becomes resident after a day and a night have passed, he must remove them as well.
Whoever breaks his wuḍūʾ while resident and then wipes while traveling takes the ruling of a traveler as regards the duration of wiping, so long as he does not become resident. It is stated in ʿUmdat al-Sālik wa ʿUddat al-Nāsik (Vol.1/p.15): “If he wipes over both [socks] or one of them while resident and then travels, or wipes while traveling and then becomes resident, or doubts whether he began the wiping while traveling or while resident, he completes only the wiping period of a resident. But if he broke his wuḍūʾ while resident and wiped while traveling, he completes the period of a traveler, whether or not the full time of a prayer had passed over him while resident.” And Allah Almighty knows best.