C because the electrons is what’s used to determine the reactivity
We are provided with the amount of energy released when one mole of carbon reacts. We mus first convert the given mass of carbon to moles and then compute the energy released for the given amount.
Moles = mass / atomic mass
Moles = 23.5 / 12
Moles = 1.96 moles
One mole releases 394 kJ/mol
1.96 moles will release:
394*1.96
= 772.24
The enthalpy change of the reaction will be -772.24 kJ
<span>It generally does not mean that there is double the oxygen, but in this case there is double, because the subscript number tells how many atoms of that element are in a particle. In this case, there are two of the oxygen, hence the DI-oxide verbiage, and one of the carbon. When there is only one, it's MONOxide, to indicate only one atom.</span>