[shovel]

Hello,
I had my chemistry final today and was wondering about one of the questions: When heated, a solid orange substance releases colorless gas and turns green. Is it a compound or a mixture?
Thanks for any explanations!
Edit: I read the rules and I am supposed to show what I have done to solve the problem. I already narrowed it down to these two from the four original options. I am stuck here because I don't know what to look for that will help me decide between the two.

[Borek]

Can you quote the entire question?

[shovel]

So I got more info about the question, and it apparently also said that the substance was "pure" so I am now pretty sure the answer is compound, which is what I thought.

[Borek]

It is about as ambiguous as something can be.

[jeffmoonchop]

We don't know what the question is, or the choice of answers, or how you worked it out.

[MNIO]

mixtures are often a blend of colors...
  a yellow substance + a blue substance mixed together = a green substance

but you don't have that...
  you have an orange substance that turns into a colorless gas + a green residue
  that's indicative of a decomposition reaction not separation of mixed components
  right?  colorless + green ≠ orange does it?

you had a compound that decomposed not a mixture