Answer:
56
Explanation:
The mass number of an atom is a sum of its number of protons and neutrons. Iron (Fe) has an atomic number of 26. This means that it has 26 protons. Since we know it has 26 protons and are told it has 30 neutrons. The mass number of this atom of Iron is 26+30 = 56
Hope this helped!
 
        
             
        
        
        
Balance each one by adding electrons to make the charges on both sides the same: 
Sn--> Sn2+ + 2 e- 
Ag+ + 1 e- --> Ag 
Now, you have to have the same number of electrons in the two half-reactions, so multiply the second one by 2 to get: 
2 Ag+ + 2 e- --> 2 Ag 
Now, just add the two half reactions together, cancelling anything that's the same on both sides: 
2 Ag+ + Sn --> Sn2+ + 2 Ag 
And you're done.
        
             
        
        
        
Answer:
Cyanide
Explanation:
<em>Molecular Structure of Each Answer</em>
A:  CN-
B: NO3-
C: OH-
D: SO4 2-
As you can see, only A (Cyanide) is the only compound that does not contain oxygen, meaning it is NOT an oxyanion.