Answer:
O=O bond
Explanation:-
Note it down that the bond having highest Hydrogen enthalpy has strongest bond.
Now
- O=O(495KJ/mol)
- O-O(146KJ/mol)
- O-H(467KJ/mol)
- H-H(432KJ/mol)
Hence

It would be Rubidium chloride.
C because it has to do with opposite motions and stuff
Al is 1.
As for NO3,it is one entity, an the whole thing is being multiplied by 3. Use the distributive property from math.
N is 3.
And O is 9.
In total, there are 13 atoms.