The sample contains both Fe and oxygen
The mass of the sample is 36 g
28 g are Fe and 8 g are O
So to find the percent composition we can calculate using the following formula
Percent composition of the element = mass of the element / mass of the sample x 100%
Percent composition of Fe = 28 g / 36 g x 100 % = 77.8%
Percent composition of O = 8 g / 36 g x 100 % = 22.2%
N=5.0 mol
m=3.2 kg
C=n/m
C=5.0/3.2≈1.6 mol/kg
Answer: The final energy is 1,700 J
Explanation: According to first law of thermodynamics:

=Final energy-initial energy=Change in internal energy
q = heat absorbed or released
w = work done by or on the system
w = work done by the system=
{Work done by the system is negative as the final volume is greater than initial volume}
q = +500J {Heat absorbed by the system is positive}
w = work done by the system = -300J


I believe the correct answer from the choices listed above is option 2. From the balanced equation, the energy is absorbed as the bonds are broken. Energy is needed to be supplied for the bonds to be broken.
Hope this answers the question. Have a nice day.
Answer:
Absorbed
Released
Released
Explanation:
The formation of a cation is an endothermic process because energy must be absorbed in order to remove an electron from an atom.
Similarly, energy is evolved when an electron is added to an atom to form a negative ion.
The formation of an ionic compound is an exothermic process. Since ionic compounds are more stable than the individual ions separated by a distance, the excess energy of the isolated ions is evolved when the ionic compound is formed.