The rms speed of particle of mass 5 x 10-17 kg. in their random motion in air at NTP will be (Boltzmann's constant K = 1.38 x l0-23 J/K)

GivenMass of the particle m = 5 × 10-17 kgAbsolute temperature = 273 KThe rms speed of the particle is given by vrms = 3KTm = 3×1.38×10-23 ×2735×10-17          = 226×10-6 = 15 × 10-3 m/s