Explanation:
Given that,
Charge 1, 
Charge 2, 
Distance between charges, r = 0.0209 m
1. The electric force is given by :


F = -492.95 N
2. Distance between two identical charges, 
Electric force is given by :




Hence, this is the required solution.
DEFINITION:::::;;The type of reactions in which energy is releases to the environment are called Exothermic reactions.
EXAMPLE::: formation of carbon dioxide and urea formation are actually the examples of exothermic reaction..
Hope it helps