What is a tonic note?

A tonic note is the note that names the key.

Explanation:

The tonic note is one of the most important notes in music. It is one of the indicatiors of what key a piece of music is in.

where is the excerpt?

including the octave, the answer would 8 notes in a major scale with one note being played twice. ex) c major scale includes: c, d, e, f, g, a, b, c

notice that c is played twice

however, if you were to ask me how many different notes are in a major scale- the answer would be 7.