<span>NaCn contains an Na+ ion and a CN- negative ion, so it has an ionic bond. The CN ion is formed by a covalent bond of the carbon and nitrogen, so it also has a covalent bond. Therefore, the answer is NaCN.</span>
        
                    
             
        
        
        
Answer:
Explanation:
Step 1 
The question is based on the concept of PH and pOH calculations.
 
pH is defined as negative logarithmic of hydronium Ion concentration.
 
while pOH is defined as negative logarithmic of hydroxide ion concentration of the solution.
Step 2 
[H+] = 7.7*10-7  M  
pH = -log[H+]  
     = -log ( 7.7*10-7 )
      = 6.12 
Step 3
pOH = 14 - pH 
    = 14 - 6.11 
   = 7.89