The two objects, both having a charge of +1 C, will repel each other due to having the same type of charge (positive). According to Coulomb's law, the force between two charged objects can be calculated, and it increases with the magnitude of the charges and decreases with the square of the distance between them.
Given that both charges are +1 C and are only 10 mm apart, the force will be quite strong, as the relationship indicates a significant repulsive force due to the proximity of the charges.
Thus, the correct response is: repulsive, strong.