How many moles of NH3 would be needed to produce 1.99 x 1025 molecules of H20? Assume the reaction is 100% efficient and that oxygen gas is present in excess. A. 49.6 moles
B. 8.93 moles
C. 3.97 moles
D. 22.0 moles

** please answer quickly !! thank you :)

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)