# The temperature at which the velocity of Helium is four times the velocity of Hydrogen at NTP is?

(A) 7420 K (B) 3710 K (C) 576 K (D) 2194 K

$v_{rms}$ of Helium $= 4 \times v_{avg}$ of Hydrogen.
$\Rightarrow \large \sqrt \frac{3\times RT}{4}$ $=4 \large \sqrt \frac{R \times 273}{\pi \times 2}$
$\Rightarrow \large\frac{3T}{4}$$= \large\frac{16\times 8 \times273}{2\pi}$
$\Rightarrow T = 27.18 \times 273 = 7419.1K$