<span>Zn(OH)4= ; -2 = -4 + ?, Zn = +2 , the -4 is the charge on the 4 OH- ions.
NO3- + 6 H2O + 8 e- -------> NH3 + 9 OH-
( Zn + 4 OH- ----> Zh(OH)4= + 2e-) x 4
7 OH- + NO3- + 4 Zn + 6 H2O -------> NH3 + 4 Zn(OH)4</span>
B I think, it has layers that protects the cells nucleus
Atomic models were developed through indirect observation even though no one had seen an atom. There were many experiments of which I know nothing about, but in the end the scientists managed to come up with a formula and various models to describe atoms.