The Mobility of a Tetramethylammonium, [N(CH₃)₄]⁺, Ion in Dilute Aqueous

The mobility of a tetramethylammonium, [N(CH₃) ₄]⁺, ion in dilute aqueous solution is 4.65*10⁻⁸ m² s⁻¹ V⁻¹ at a temperature of 298 K. Estimate the radius of the ion, given that the viscosity of water at this temperature is 1.00 mN s m^-2.

A) 1.2 Å
B) 2.4 Å
C) 1.6 Å
D) 1.8 Å