b
દ બ્રોગ્લીની તરંગ લંબાઈ \(\lambda \,\, = \,\,\frac{h}{{mv}}\,\,\,\)

\(\therefore \,\,v\, = \,\,\frac{h}{{m\lambda }}\,\,\)

\( = \,\,\frac{{6.6\,\, \times \,\,{{10}^{ - 34}}}}{{1.675\,\, \times \,\,{{10}^{ - 27}} \times \,\,1.40\,\, \times \,\,{{10}^{ - 10}}}}\,\,m{s^{ - 1}}\)

ન્યુટ્રોન ની ગતિ ઊર્જા\( \frac{1}{2}\,m{v^2}\, = \,\,\frac{1}{2}\,\, \times \,\,(1.675\,\, \times \,\,{10^{ - 27}})\,\)

\(\,\,{\left[ {\frac{{6.6\,\, \times \,\,{{10}^{ - 34}}}}{{1.675\,\, \times \,{{10}^{ - 27}} \times \,\,1.40\,\, \times \,\,{{10}^{ - 10}}}}} \right]^2}\)

\( = \,\,\frac{{{{(6.6\,\, \times \,\,{{10}^{ - 34}})}^2}}}{{2\,\, \times \,\,1.675\,\, \times \,\,{{10}^{ - 27}} \times \,\,1.4\,\, \times \,\,1.4\,\, \times \,{{10}^{ - 20}}}}\)

\( = \,\,6.69\,\, \times \,\,{10^{ - 21}}\,J\)