Question

The temperature at which oxygen molecules have the same root mean square speed as helium atoms have at 300 K is:

(Atomic masses : $He=4u,O=16u)$

• A. 300 K
• B. 600 K
• C. 1200 K
• D. 2400 K

Answer 1

Answer: (D)

2400 K

$V_{RMS}=\sqrt{\frac{3RT}{M}}$, where M is the molecular mass.
$\sqrt{\frac{T_1}{M_1}}=\sqrt{\frac{T_2}{M_2}}$
$\sqrt{\frac{300}{4}}=\sqrt{\frac{T_2}{32}}$
$T_2=2400K$