The correct answer is letter C
Answer: The state of maater for HgBr is solid.
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation is:

Idk tbh srry man am in quarantine so I have a big packet to do
Charge = Number of Protons - Number of Electrons = 4
So, Your Answer would be: 4
Hope this helps!