What is the purpose of the proton motive force? A. Powers the phosphorylation of ATP to ADP. B. Powers the phosphorylation of ADP to ATP. C. Powers the production of high energy electron carriers. D. Powers the ability to generate more redox reactions.

Explanation:

The proton motive force; is the free energy released during the oxidation of NADH or FADH2  and it is  stored both as an electric potential and a proton concentration gradient across the inner membrane.  

The purpose of proton motive force is that the movement of protons back across the inner membrane, driven by this force, is used to the synthesis of ATP from ADP and Pi by  ATPase/ ATP synthase (F0F1 complex ).

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6