A 0.6-m3 gas tank holds 5 moles of nitrogen gas (N2), at a temperature of 320 K. The atomic mass of nitrogen is 14 g/mol, the molecular radius is 3.0 × 10-10 m, and the Boltzmann constant is 1.38 × 10-23 J/K. The root-mean-square speed (thermal speed) of the molecules is closest to: