Depending if you were going up, you would be seeing an increase in relative ionization energies in a particular group on the periodic table, and vice versa, if you go down the group, an decrease in the relative ionization energies.
In the Lewis structure, each single bond drawn between elements contain two electrons. The electron dots represent the lone pairs. These are the electrons that take part in the reaction. To obey the octet rule, the oxygen must have eight electrons around it. The hydrogen is exempted from this rule. Therefore, you have to show two electrons.
B. examining the number of chromosomes in population
Your answer would be D. As the circulatory system pumps oxygen rich blood through the body, and the respiratory system helps you to breath. Hope this helps!
Many nitrogen atoms have seven neutrons<span> (14-7 = 7). Some atoms of nitrogen, however, have eight electrons. They are atoms of N-15, an isotope of nitrogen. In a neutral atom, the number of protons must equal the number of electrons.</span>