#### Answer

a. +90.7 kJ
b. 181.4 kJ
c. -181.4 kJ

#### Work Step by Step

a. The reaction shows that for every mole of mercury produced, 90.7 kJ is consumed. Therefore, to produce one mole of mercury, we would need 90.7 kJ of energy,
b. The reaction shows that for every half a mole of $O_2$ produced, 90.7 kJ of energy is consumed. Therefore, for every mole of $O_2$, $2*90.7=181.4$ kJ of energy is consumed.
c. The reaction shows this forward reaction results in the consumption of 90.7 kJ of energy. Therefore, the reverse reaction would release -90.7 kJ of energy. Finally, because each of the coefficients are doubled, the total change in energy is $-90.7*2=-181.4$ kJ.