Chromosomes have genes that determine specific thing about a person (hair color, eye color, how tall or short a person is etc....).
It might be c, because he came up with the plum pudding model. or it might be that atoms of the same element are identical, but that's not true cuz ions are different and isotopes are different.
The balanced reaction that describes the reaction between lithium and nitrogen to produce lithium nitride is expressed N2 + 6Li = 2Li3N. Hence for 12 moles of lithium given, there are 4 moles of lithium nitride produced. Answer to this problem is 4 moles.