Question

If the velocity of hydrogen molecule is $5\times {10}^{4}cmse{c}^{-1}$, then its de-Broglie wavelength is:

• A. $2\stackrel{o}{A}$
• B. $4\stackrel{o}{A}$
• C. $8\stackrel{o}{A}$
• D. $100\stackrel{o}{A}$

Answer 1

The correct option is B $4\stackrel{o}{A}$

According to de-Broglie,

$\lambda =\frac{h}{mv}=\frac{6.62\times {10}^{-27}ergsec}{\frac{2}{6.023\times {10}^{23}}\times 5\times {10}^{4}cm/sec}=4\times {10}^{-8}cm=4\stackrel{o}{A}$