Answer:

Explanation:
From the question we are told that:
Mass of mixture 
Mass of Barium 
Equation of Reaction is given as

Generally the equation for Moles of Barium is mathematically given by
Since

Therefore

Generally the equation for Mass of Barium is mathematically given by

Therefore


D 4 grams
i need to write a couple more character for explanation so there
C and A because the product of a matter will always be the same and just google A.
Answer and Explanation
The isomer picked is the N-Propylamine.
It has a lone pair of electron available on the electron rich Nitrogen and no formal charge.
Since it will be hard to draw the Lewis structure in this answer format, I'll attach a picture of the Lewis structure to this answer.
The lone pair of electron is shown by the two dots on the Nitrogen atom.
C.
Protons is 8 so the atomic number will be 8.
Number of neutrons= atomic mass - atomic number
16-8 = 8.