I have a question

Take a slash chord maybe C/G. Can the G be any note from the scale of C major?

Like C/F, C/A, C/B and vice versa.

If you're asking if there are any rules to follow with a slash chord, It can be any note you want.

All it means is
[Any chord] / [Any bass note]

Sticking with the key of the song is a good idea though. If you had a song in the G major scale, you'll want a chord like:

C /
Any chord In G major /

NOTE: There are always exceptions and you don't have to follow scales, but a lot of music does. It can be whatever you want.

You can't change them to your fancy from what's written down on a tab however if that's what you mean.
There's a good chance that what I've written above is useless and if you take any of the advice it's your own fault.
Last edited by Silent Murder at Sep 7, 2011,
To add to that, when you play a G/F#, even though it is a Gmaj7, you call it a G/F# so long as the F# is in the bass register. Same with G/E (G6) and such.
Quote by EndTheRapture51
who pays five hundred fucking dollars for a burger