Answer:
A positive and negative ion.
Explanation:
Ionic bond:
It is the bond which is formed by the transfer of electron from one atom to the atom of another element.  
Both bonded atoms have very large electronegativity difference. 
The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.
For example:
Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion.  Sodium have one valance electron while chlorine have 7 valance electrons. In order to complete the octet chlorine require one electron while sodium need to lose its one electrons. That's why when both atom combine sodium lose its electron and becomes positive ion i.e cation while chlorine accept its electron and becomes negative ion called anion and bond between them is ionic bond.
 
        
                    
             
        
        
        
The Answer is D cause of the people going back and forth.
        
                    
             
        
        
        
The amount of oxygen bound to hemoglobin is 98.5% 
        
                    
             
        
        
        
Answer: 4 hydrogens
Explanation:
This is what the structure will look like C=C. Remember that it's important that all structures have a complete octet. As it looks right now each carbon is sharing 4 valence electrons so each needs 2 more bonds to hydrogen complete its octet.