Like naphthalene balls, 1,4-Dichlorobenzene (para-dichlorobenzene) balls are used to kill moth larvae by their slight sublimation at room temperature. A reasonable amount of these were left exposed in a 5.0 m by 5.0 m by 5.0 m room at 25 °C. Assuming that these spheres are pure solid para-dichlorobenzene and that the K_c value for the sublimation reaction is 2.72×10⁻¹³ at 25 °C, determine the number of gaseous para-dichlorobenzene molecules present in the room at equilibrium.

C₆H₄Cl₂ (s) ⇌ C₆H₄Cl₂ (g)