The ozone (O₃) molecule consists of three oxygen (O) atoms. The central oxygen (O) atom forms a single covalent bond with another oxygen atom and a double covalent bond with the third. It has two resonance structures that are shown below.  

O=O⁺-O^– ↔ O^–-O⁺=O

To determine the formal charge of ozone, we must first calculate the formal charges on the three oxygen atoms.

i. O=O⁺-O^–

Oxygen 1

V = 6, N = 4, B = 4

Therefore,

q_f = 6 – 4 – 4/2 = 0

Oxygen 2

V = 6, N = 2, B = 6

Therefore,

q_f = 6 – 2 – 6/2 = 1

Oxygen 3

V = 6, N = 6, B = 2

Therefore,

q_f = 6 – 6 – 2/2 = -1

The net formal charge is: 0 + 1 – 1 = 0

ii. O^–-O⁺=O

Oxygen 1

V = 6, N = 6, B = 2

Therefore,

q_f = 6 – 6 – 2/2 = -1

Oxygen 2

V = 6, N = 2, B = 6

Therefore,

q_f = 6 – 2 – 6/2 = 1

Oxygen 3

V = 6, N = 4, B = 4

Therefore,

q_f = 6 – 4 – 4/2 = 0

The net formal charge is: -1 + 1 + 0 = 0

The formal charge of both the resonance structures of ozone is zero. It means that both these structures are stable and contribute equally to the molecule’s overall hybrid structure.