What is the ruling on doubting whether one or two prostrations were performed?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
If a worshiper is in doubt regarding the number of units (rak'ahs) or prostrations (sajdahs) performed, he must build upon the minimum (i.e., assume the lower number) and perform the prostration of forgetfulness (Sujud al-Sahw) before the Salam at the end of the prayer. This is based on the report from ‘Ata’ ibn Yasar that the Messenger of Allah ﷺ said: 'When anyone of you is in doubt about his Salat (prayer) and does not know how many he has prayed, three or four (Rak'at) he should cast aside his doubt and base his prayer on what he is sure of. Then, he should perform two prostrations before Taslim (salutation). If he has prayed five Rak'at, they will make his Salat (prayer) an even number for him and if he has prayed exactly four, they (i.e. two prostrations) will be humiliation for the devil..' (Narrated by Abu Dawud).
It is stated in Al-Muqaddimah al-Hadramiyyah: 'If one doubts [whether he performed] a bowing (ruku’), a prostration, or a rak'ah, he must perform it and prostrate [for forgetfulness], even if the doubt is removed before the Salam—unless the doubt is removed before he performs what would potentially be an addition. Thus, if he doubts whether he prayed three or four, he is obligated to build upon the minimum.' And Allah the Exalted knows best.
Is it permissible for the children of a deceased father to settle his debt from the Zakah (obligatory charity) money due on them?
It is impermissible to use the Zakah of one`s money for settling the debts of the deceased. However, children should settle the debts of their deceased parents out of filial piety. And Allah Knows Best.
Is it permissible to pay the Zakah (obligatory charity) for settling the debt of a deceased relative?
It is impermissible to pay the Zakah for settling the debt of the deceased since Zakah is paid to eligible recipients who are alive. As for the debts of the deceased, they are to be settled from the estate before dividing it amongst the heirs, but if the deceased didn`t leave an estate, then it is desirable for his/her heirs to settle those debts if they can afford them. And Allah Knows Best.
What is the ruling on applying perfume while fasting?
Applying perfume does not break the fast. However, it is better to avoid it, as fasting is a practice of simplicity and restraint, while perfume is a form of luxury.