The correct answer is A.
B is incorrect because that only applies to nuclear fission.
C is incorrect because it only applies to nuclear fusion.
D is incorrect because energy can be neither created nor destroyed meaning that this statement is physically impossible,
The answer would be C there would be 6 nonbonding electrons and 2 bonding electrons.
As the atomic mass of iron is 55.847u
We say that it is the mass of one mole of iron.
By formula it can be find by
No.of mole=mass in g/molar mass
Mass in gram = no.of mole x molar mass
No.of mole =1
Molar mass = 55.847g
Mass in gram = 1x55.847
= 55.847g of Fe