Elaborate on how the isotopes and their relative abundances affect the average atomic mass of an element.
a. average atomic mass comes from the mass of the isotope nucleus and is proportioned by the relative abundances.
b. the different masses of isotope electrons gives the relative abundance and average atomic mass of the isotopes.
c. isotope mass both varies in neutron numbers and is weighted by its relative abundance to give the average atomic mass.
d. when calculating the average atomic mass of the element, the number of protons gives the relative abundance of the isotopes.

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.