What is the scale of this melody

[regards]

To be honest, I'm confused. The amount of the note “a” makes it sound modal. Does it begin C Maj and then becomes modal?

Regards,
Regards

[brogers70]

Well, it starts and ends on G, all the notes are natural. That would make it mixolydian mode. At least that's how I'd think of it, without any other context.

[quantum]

More context would help in securing an answer to your question.  What comes before and after this melody, how does it cadence, what harmonies are used with it. 

Using the given example, here is what can be observed:

Pitch classes in use:
A, C, D, E, F, G

Ambitus:
one octave, A to A

Cadences:
A to G, though it is difficult to say if this truly is a cadence point or if its only part of a longer melody. 


Here are some ways I might describe this excerpt:
Mixolydian hexatonic, authentic ambitus, with omitted 3th degree.
Ionian hexatonic, plagal ambitus, with omitted 7th degree.
Aeolian hexatonic, authentic ambitus, with omitted 2nd degree.