Why do nitrogen molecules have a bond order of three, whereas oxygen molecules have a bond order of two?

This is because the electron configuration of Nitrogen is 2.5 while that of oxygen is 2.6. This is putting into perspective that the stable configuration for this period of elements is 2.8. Therefore Nitrogen would require 3 electron to reach stable configuration (2.8) while oxygen requires 2. This means that in sharing of electrons in covalent bonds, nitrogen will form three(3) bonds while oxygen will form two (2).

a time line cause it goes from 685 to 978

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.