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Chemistry Level 3

The atomic masses of Helium and Neon are 4 and 20 amu respectively. What is the ratio of de Broglie wavelength of He gas at $-73^\circ C$ compared to that of Ne gas at $727^\circ C$ ?

The answer is of the form $\dfrac{a}{b}$ , where $a$ and $b$ are coprime positive integers. Enter your answer as $a+b$ .