The coefficient of viscosity `eta` of a gas depends on mass of the gas molecule, its effective diameter and its average speed. It is known that diameter of helium atom is `2.1xx10^(-10)` m and its coefficient of viscosity, at room temperature is `2.0 xx 10^(-5)` kg `m^(-1)s^(-1)`. Estimate the effective diameter of `CO_(2)` molecule if it is known that `eta` at room temperature for `CO_(2)` is `1.5 xx 10^(-5)` kg `m^(-1)s^(-1)`.