If you apply for citizenship in another country your US citizenship is automatically revoked. The US does not recognize dual citizenship. You revoke it in writing at a US embassy, outside the US.
Yes, The residents of US territories have US citizenship
The US recognizes dual citizenship.
No. The US president MUST have US citizenship only.
If you are born in the US you obtain US citizenship by birth. Another way to obtain citizenship is through the naturalization process by applying for US citizenship using Form N-400 if you are eligible.
Yes dual citizenship is allowed for US citizens.
Mark Zuckerberg did not renounce his US citizenship. He did, however, give up his US citizenship while acquiring citizenship in other countries to avoid double taxation on his assets.
US citizenship can only be renounced in writing at a US embassy (i.e. outside the U.S.). Be sure you have citizenship in another country before doing this.
NoSee US Citizenship and Moving Abroad.http://www.richw.org/dualcit/faq.html
Yes only if that person is a American applying for dual citizenship in Brazil. A person from Brazil would be unable to keep citizenship in Brazil if they wanted US citizenship. because the US requires you to give up your citizenship to all other countries except Canada citizenship.
If he is a US citizen that happens to be in Turkey, then yes. If he has Turkish citizenship, he will need to attain US citizenship (either dual citizenship or give up his Turkish citizenship for an American one).
If the parents are US citizens, then the child gets duel citizenship (citizenship in the country he/she is born in [depending on local laws], and US citizenship). Any person naturalized in the US or by American parents is a US citizen.