As the population increases, so does household waste. the most environmentally friendly, and also realistic, solution to this state's household waste problem would be
a) more extensive use of landfills.
b) building underground waste storage tanks.
c) recycling or composting most of the waste.
d) burning the waste and using the ashes for fertilizer.

n has four pairs of electrons in the valence shell, electrons repel one another ,n has 7 protons in its nucleus, and since n has 7 protons, it must fill the second shell, giving it 4 pairs of electrons. the electrons form 3 bonds and 1 lone pair of electrons. each pair of electrons repels the other pairs, so they are equally far apart.

so all of the above

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)