Answer:
I think its A
Explanation:
Because the reason why airplane have closed windows is because we can't breathe in carbon dioxide when we go up. Of course there is oxygen just not a lot as we go up. Why would there be helium in the air? We would sound weird when we skydive.
B. defiantly b. because it can survive in most climates.
Answer:
It would turn black. H H 6. It would not turn black. does Briefly explain why you chose either a or b. Because it does not contain courbon or any such compound which change color upon heating