The ratio of number of oxygen atoms (O) in 16.0g ozone (O), 28.0 g carbon monoxide (CO) and 32.0g oxygen (O₂) is :

(Atomic mass :C =12, O =16 and Avogadro’s constant N_A = 6.0$\times$10²³ mol^-1)

Molar mass of O₃ = 48

Given 16 g O₃ . So no. of moles of O₃ = 16/48 = ⅓

1 mole = 3 ×N_A oxygen atoms

So 1/3 mole = N_A×3×1/3 no of atoms

= N_A oxygen atoms

Molar mass of CO = 28

Given 28 g CO. So no of moles = 28/28 = 1

No. of atoms = 1×N_A = N_A

Molar mass of O₂ = 32

Given 32g O₂

No. of moles = 32/32 = 1

No.of atoms = 2×N_A = 2N_A

So the ratio is 1:1:2