The atomic masses of He and Ne are 4 and 20 a.m.u., respectively.… - Vidyadip

MCQ

The atomic masses of $He$ and $Ne$ are 4 and $20 \ a.m.u$., respectively. The value of the de Broglie wavelength of He gas at $-73^{\circ} C$ is $"M"$ times that of the de Broglie wavelength of $Ne$ at $727^{\circ} C$. $M$ is

A
$3$
B
$4$
✓
$5$
D
$6$

✓

Answer

Correct option: C.

$5$

c
$\lambda=\frac{h}{\sqrt{2 m ( KE )}} \quad KE \propto T $

$\frac{\lambda_{ He }}{\lambda_{ Ne }}=\sqrt{\frac{ m _{ Ne } KE _{ Ne }}{ m _{ He } KE _{ He }}}=\sqrt{\frac{20 \times 1000}{4 \times 200}}=5 .$

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