Does ill-gotten money hinder the answering of the Du`a(supplication) and the means of subsistence?

Sins hinder the answering of the Du`a, and deprive the sinner from means of subsistence; whereas, acts of obedience facilitate making a living. Allah, The Almighty, says in the Holy Quran: “And for those who fear God, He (ever) prepares a way out. And He provides for him from (sources) he never could imagine.”{At-Talaq/2-3}.

What is the semi-circular structure abutting the Holy Kabah?

It is the Black Stone of the Holy Kabah, and one should pass from behind it while offering Tawaf(circumambulation) because it is part of the Kabah.

Should a minor fulfill his vow?

The vow of a minor is countless because he isn`t required to meet the Sharia rulings at such an age, and it is desirable for him to fulfill that vow once he reaches puberty.

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? This is knowing that there is no drawing of lots; only one or two cards are purchased to commence the contest.