Explain why combustion reactions generally go to completion at all temperatures. Sometimes nitrogen gas (black) reacts with oxygen gas (white) to

Okay so I have no clue what's going on in these two questions. Attachment below:

Explain why combustion reactions generally go to completion at all temperatures. Sometimes nitrogen gas (black) reacts with oxygen gas (white) to produce nitric oxide (black-White).This reaction is endothermic. Write out the balanced chemical reaction and draw a reaction coordinate diagram, as well as a PEC diagram. Which direction would the reaction go at low temperature?