If this diagram is accurate, would the 7th of a Bmin7 be formed from a minor 7th interval or a major 7th interval, e. g. A-natural or A-sharp? I'm assuming A-natural. If this line of thinking is wrong, what is the proper way to denote the 7th interval and also, while at it, how to determine the 9th?
I've narrowed down my confusion: the composition of a triad chord is the 1st, 3rd, and 5th interval from the root. However, some cases notes in this triad are a sharp or flat note. Is there any system or rule set that can be universally followed to determine those cases? or is it just by memory?
Ok so I've narrowed down (based on answers below) that whether a note is a sharp or flat is determined on the key. So I guess the answer to my question is how to determine a key of a note through some sort of rule set, as in do this, this, and this to determine the key of C. If this doesn't exisit, I will result to memorization I assume.
Also have determined so far that the diagram below is wrong because occasionally a chord will start with a sharp and have sharps as the 3rd interval, so that isn't represented below.
So based on feedback below, to know whether notes in a chord are sharp are flat is basically knowing the scale. The pattern I was seeking was TTSTTTS, thanks tim. It is Tone & Semi Tones. I will have to do some more research but thank you everyone for contributing. Please feel free to add more thoughts below.