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I am a bit confused about questions 11-13. I answered them, but I am not convinced by my reasoning behind my methods.
I attached both the questions and the corresponding graph.
Thank you!

Amount of energy needed to break the bond is exactly same to the amount of energy released when a bond is formed.In the curve ,bond is formed at the lowest energy point in the curve(most stable).Atoms when are completely separated and far away from each other then their interaction energies are zero and when they start coming closer and attraction increases ,energy decreases. However ,a point will reach when nuclei positive charges  of each atoms and electrons clouds of each atom start repelling. At this point repulsive forces increases and this results in increase of energy in the curve.

Amount of energy released depends on the number of moles of bonds formed.
A + B ----> A-B
If one mole of each atom combines to form one mole of compound ,it means only one mole of bond is formed.
Q 13 is correct.