Q 11-12-014NEETJEE MainEasy
The rms speed of oxygen molecules at $300$ K is about ($R = 8.31$ J mol$^{-1}$ K$^{-1}$, molar mass $32$ g mol$^{-1}$)
Answer: (A) $483$ m s$^{-1}$
Concept. $v_{\text{rms}} = \sqrt{\dfrac{3RT}{M}}$ with $M$ in kg/mol.
Step 1. Substitute.
$$v_{\text{rms}} = \sqrt{\frac{3 \times 8.31 \times 300}{0.032}} \approx 483\ \text{m s}^{-1}$$
Answer. $483$ m s$^{-1}$ (Option A).
Solution by Sreeraj P, M.Sc Physics