Electric Force, Field, and Potential

What factors determine the electric potential energy between two charged particles?

Two point charges, $q_1 = +3,\text{C}$ and $q_2 = -4,\text{C}$, are separated by a distance of $2,\text{m}$. What is the electric potential energy of this system? (Use $k = 9 \times 10^9 ,\text{N} \cdot \text{m}^2/\text{C}^2$)

Three charges are arranged as follows: a +2q charge at (0,0), a -q charge at (a,0), and a +q charge at (0,a). What is the total electric potential energy of this system?

A system contains four charges. How many unique pairs of charges are there in this system?

Four charges are arranged in a square with side length 'a'. Two charges are +q, and two are -q, arranged alternately. What is the total electric potential energy of this system?

A charge of +2 C is placed at a point where the electric potential is 10 V. What is the electric potential energy of this charge at that point?

A +q charge starts from rest at point A and moves to point B due to the electric force. At point A, the electric potential energy is $U_A$, and at point B, it is $U_B$. If the mass of the charge is m, what is its final velocity at point B?