Question

The table below shows the distance between the atoms in an atom pair. All four pairs of atoms have the same amount of electric charge.

Pair of Atoms Distance Between the Atoms
A & B 4 units
C & D 9 units
P & Q 25 units
X & Y 16 units

Which pair of atoms are repelled from each other with the most force?
A.
pair X & Y
B.
pair C & D
C.
pair A & B
D.
pair P & Q

Answer 1

C. pair A & B

Coulomb's law: F ∝ 1/r^2 for equal charges, so the smallest separation (4 units for A & B) gives the largest force.