Is it incumbent on a father to cover the marriage costs of his son if the latter couldn`t afford them?

The son should seek the help of his relatives in order to convince his father to do the aforesaid, and the father should make sure that his son doesn`t commit fornication through helping him to get married, and Allah will reward him for doing so.

What is the ruling on a person who insists on praying in a specific spot and becomes angry if someone else prays there?

ruling on a person who persists in praying in a specific spot and becomes angry if someone else occupies it

Is it incumbent on a husband to pay the alimony of his wife if she had left him and stayed at her parent`s without his permission?

When a wife leaves her house, and stays at her parent`s without asking her husband, she is considered a Nashiz (wife who refuses to abide by her husband’s orders), and so she doesn`t deserve an alimony.

A person prays in a certain spot within the rows of the mosque, and gets angry if someone else prayed at his spot. What is the ruling on this behavior?

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                                                                                                                                                                                                                              Prophet Mohammad (PBUH) make it prohibited for a Muslim from having/taking a certain spot in the mosque when performing prayers if they arrived and find it occupied, furthermore; it is the religious duty on others (praying people) to offer a piece of advice to alert the ones who don't know, that whoever reaches a spot first at the mosque having a priority/privilege upon others in that spot. And Allah Knows Best.