# Calculate the wavelength (in nanometer) associated with a proton moving $1.0\times 10^3ms^{-1}$ (mass of proton=$1.67\times 10^{-27}$kg and $h=6.63\times 10^{-34}Js)$

$(a)\;0.032nm\qquad(b)\;0.40nm\qquad(c)\;2.5nm\qquad(d)\;14.0nm$

$\lambda=\large\frac{h}{mu}=\large\frac{6.63\times 106{-34}}{1.67\times 10^{-27}\times 1.0\times 10^3}$
$\Rightarrow 0.397\times 10^{-9}m$
$\Rightarrow \approx 0.40\times nm$
Hence (b) is the correct answer.