Your answer will be B because sodium and chlorine and both elements and two elements combine to make a compound
They have a full valence shell (8 electrons in the outer shell) so they are the most stable elements on the periodic table. Therefore, they do not need to react to other elements to gain or lose elections to become stable.
NH3 is soluble in water because it has the same amount of intermolecular forces as water. NH3 is a polar molecule and water is a polar molecule so they dissolve each other. NCl3 does not dissolve in water because it is a nonpolar molecule which is different with water. NCl3 is nonpolar due to the difference in electronegativities between 3 atoms of Cl and 1 atom if N2.
