Should missed Sunnah prayer be made up?
Making up missed voluntary acts of worship is from Sunnah.
Is Iddah (waiting period) incumbent on an old woman whose husband had died?
Upon the death of the husband, Iddah is incumbent on the wife regardless of their age. And Allah Knows Best.
Is performing Umrah an obligation for who is capable. Is he accountable for not performing it in this case?
Umrah is an obligation once in a lifetime for every Muslim. When physical and financial ability is present, it is preferable to perform Umrah, as well as Hajj. If one can afford to perform Umrah but not Hajj, then they should begin with Umrah, especially since Hajj nowadays is not accessible to everyone who wishes to perform it. In contrast, Umrah is more open and easier to undertake. And Allah knows best.
What is the ruling on taking part in an online contest to win a prize of 100,000 dollars in return for answering thirty questions in different fields of knowledge and science? Knowing that there is no drawing of lots; only one or two cards are purchased to commence the contest.
Praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
This is a form of gambling, which is impermissible to participate in, because the people in charge of this online contest increase the value of the calls to compensate for the value of the prizes. And Allah The Almighty Knows Best.