Interrogative sentence in Portuguese may be formed by placing a word indicating a question in the beginning of a sentence or by intonation of asking in a sentence.
The following are the words partaining to questions:

que	what	O que é isto?	What is this?
quem	who	Quem é o nosso professor?	Who is our professor?
qual	which	Qual é o teu nome?	What is your name?(familiar person)